feat: remove uses of rxjs patch operators

[crisbeto]

Refactors the entire codebase not to use the patch operators from RxJS, because they pollute the user's setup. Instead, opts into importing the operators directly and chaining them via the RxChain class.

Fixes #2622.

Note: I'll add some linting to enforce these changes after they get in.

[jelbourn]

Looks good, just a few comments

[jelbourn]

We can also make the constructor private so people have to use the static from and get a strict chain.
(just looked this up a moment ago)

[jelbourn]

Maybe expand the comment with something like

/**
 * Utility class used to chain RxJS operators.
 *
 * This class is the concrete implementation, but the type used by the user when chaining
 * is StrictRxChain. The strict chain enforces types on the operators to the same level as
 * the prototype-added equivalents.
 * 
 * @docs-private
 */

[jelbourn]

I'd expand to something like

/**
 * Represents a strongly-typed chain of RxJS operators.
 *
 * We achieve strict type enforcement on the chained operators by creating types that
 * *unambiguously* match specific rxjs operators. These unambiguous types are created by
 * intersecting a "brand" to the `typeof` the existing operator. The brand (a class with a private
 * member) effectively forces nominal typing for the operators. This allows typescript to understand
 * that, for example, `filter` is *`filter`* and not, say, a map of T => boolean.
 *
 * The downside to this approach is that operators must be imported in their type-coerced form
 * rather than from the normal rxjs location.
 *
 * @docs-private
 */

[crisbeto]

Addressed the feedback and sorted out the CI failures @jelbourn.

[jelbourn]

LGTM

[jelbourn]

Caretaker note: removing the prototype operators can potentially break some apps on sync

[willshowell]

For folks who come searching later, these are the operators and observables that are no longer being patched onto your Observable.prototype

Operators
-------------
auditTime
catch
debounceTime
do
filter
finally
first
let
map
share
startWith
switchMap
takeUntil

Observables
-------------
combineLatest
forkJoin
fromEvent
merge
of
throw

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