Create a quick fix for @awaitNotRequired

[bsutton]

We now have an annotation to suppress the discared_future lint when the annotated function correctly manages the future.

#46218

We need a way to surface the fact that the annotation is available.

One possible solution is to add an additional quick fix for discared_future and unawaited_future that adds the annotation to the called function.

I'm not certain if there are any quick fixes that work to change code located in another source file so that may be a show stopper.

Of course if the called function is an external package then we wouldn't want to show the quick fix.

[bwilkerson]

@srawlins