Adds an optional Source argument to DocumentReference and Query

[Qw4z1]

First draft of adding a Source enum to be able to run queries on cached documents instead of waiting for server responses (avoids extra reads) or force fetching from server (ignoring cache).

Note: I haven't been able to test the js implementation as my environment seems to be broken.

Documentation

Closes #263

[nbransby]

Look good, just need to add a test and have the CI turn green

[Qw4z1]

Added tests in a separate file to be able to toggle persistence per test. Curious to know if there is a better way to do this though...

[nbransby]

The android tests for auth failed with Failed to connect to /10.0.2.2:9099, not sure why. Also there don't appear to be any js or ios test report artifacts for the build so I'm not even sure those tests ran. @Daeda88 you probably have more insight on these than me, are the ios and js tests running correctly?

[Daeda88]

Auth test is unstable on Android for ci due to emulator speed I think. I'd just run it manually to be sure

[nbransby]

what about ios and js, ideally I would like to know the new test ran and passed

[Qw4z1]

@nbransby looks like the PR workflow has if: failure() as a condition for both upload steps. I'm no expert at this, but I assume that means that artifacts and reports are only uploaded if a test has failed, right? 🤔

[Daeda88]

They run on different machines, since those jobs are green, Im pretty sure the tests ran to completion