Add a client side channel group that listens for active channels and
subscribes/unsubscribes as the set of active changes.

Add a consumer group based on presence set

Add typing information for ChannelGroups

Fix tests for v2

ChannelGroups is a default realtime module

types: add channel group typings

consumergroup: use modulo-based hashing scheme

The `hashring` package is node-only as it depends on the native `crypto`
package. Replaced with a simple modulo hash scheme for now.

Fixes the case where the channel is already attached and the channel is
obtained with new rewind options that require a re-attach.

Updates the consumer group partitioning test to more robustly assert
that channels are partitioned across consumers.

channelgroup: make get sync, subscribe async

This matches the pattern used by Channels, which is sync to obtain the
channel and async on subscribe in order to await attachment. In the
channel group case, awaiting the subscribe awaits the joining of the
consumer group.

consumergroup: make consumerId required field

consumergroup: make hashring a required field

format: apply prettier formatting rules

jsdoc: add consumer group docs

channelgroups: add active channel name option

channelgroup: add explicit join method

Exposes the join method on the channel group, which is analogous to
attach on the channel. Uses this in tests for more robust assertions.

Additionally avoids re-attaching to the consumer group channel if
already attached, and obtains presence membership synchronously in the
join.

consumergroup: use subscribe over on

The `on` method was not reliable across clients, despite being
documented in
https://ably.com/docs/presence-occupancy/presence?lang=java#synced, so
use subscribe instead.

channelgroup: fix assigned channel processing

We need to keep the total set of active channels around as updating the
assigned channel set when the membership changes requires computing the
new assignments from the complete channel set, not the previously set of
assigned channels.

consumergroup: include consumerId in logs

consumergroups: add test for consumer group resize

test: remove explicit join from test

lint: apply formatting and cleanup

test: replace var with let

test: remove unnecessary outer try-catch

test: add prefix to channels

Avoid channel name collisions causing tests to fail from concurrent test
runs in CI.

channelgroup: detach from channel on un-assignment

channelgroup: add unsubscribe listener method

test: fix rebalance test waits for consumers

channelgroup: add leave method

test: remove dangling console logs

test: test consumer group scale down event

test: prefix consumer group channel

Similar to the active channel, we need to avoid conflicts.

consumergroup: fix current member tracking

We store the current active set of members in the hashring.

test: fix done condition w/ at-least-once delivery

Messages can be delivered more than once during a consumer group
rescaling event, so deduplicate the results when checking the end
condition.

channelgroups: use Utils.inspectError in logs

channelgroups: do not share channel object

The Channels object used by the ChannelGroup for internal channel
operations no longer shares the same object exposed on the client via
the .channels() method. This is to ensure that independent usage of an
individual channel that happens to be included in a channel group is not
impacted by its usage in the channel group.

test: tidy up leave test

Now that we can correctly handle a channel group and channel being used
independently from the same client, this tidies up the leave test to
remove the additional client previously needed.

test: rename waitForConsumers for clarity

test: rename waitForConsumers for clarity

channelgroups: do not share channel object

The Channels object used by the ChannelGroup for internal channel
operations no longer shares the same object exposed on the client via
the .channels() method. This is to ensure that independent usage of an
individual channel that happens to be included in a channel group is not
impacted by its usage in the channel group.

channelgroups: add module integration

modules: update ChannelGroups module definitions

channelgroup: add temp rewind channel group option

channelgroup: unsubscribe channel after timeout

In order to avoid keeping the channel alive, we add a configurable
timeout after which the channel will be unsubscribed if no messages are
received. This is to avoid keeping the channel active. This can lead to
missed messages if the a message is published after the client
unsubscribes and before the channel becomes inactive. This is an
acceptable edge case for the client-side simulation, especially with the
default 1h timeout.

deps: remove unused hashring types pkg

utils: remove arrIndexOf polyfill

consumergroup: rename hashring to locator

test: use async style tests for channel groups

Replaces the use of the `done()` callback with an async function style
test.

This allows us to await channel publish results and more easily handle
race conditions in tests.

channelgroup: use qualifier options

Previously we relied on a new BaseRealtime instance with it's own
Channels object to separate usage of channels in the ChannelGroup from
independent external usage of those channels from the regular
client.channels.get() method. This led to various problems with shared
Auth state such as nonces in token requests which caused connections to
terminate and tests to fail.

A simpler solution is to avoid creating a new client instance and
instead share the Channel pool, but force the library to treat channels
used from the ChannelGroup independently (with their own attachment) by
setting dummy options in the qualifier, which is used as the key in the
channel map.

This implementation does not support channels in the channel group which
already have a qualifier. This is acceptable for the experimental
client-side simulation of the feature.

Each client will be entered in the presence set once per connection, so
we need to deduplicate the presence set by clientId.

…mitter

channelgroup: emit channel assigned/active events

…events

consumergroup: emit membership updated event

Since the set of active channels are surfaced on $ably:active is a
superset of those specified by a particular channel group expression,
this commit ensures we only emit an active.updated event when the set of
channels matching the consumer group expression have actually changed.