Introduce SharedFlow collect overload and override that return Nothing

[qwwdfsad]

* Override will ensure the proper implementation of the interface
* collect extension is added as the very basic lint helper

Fixes #2789
Fixes #2502

[qwwdfsad]

I've decided not to add Nothing overload for each terminal extension as it seems to be too much of a hassle.
The basic lint for extension and core documentation should suffice

[LouisCAD]

I've decided not to add Nothing overload for each terminal extension as it seems to be too much of a hassle.

Too much of a hassle to do, or from another standpoint like maintaining?

I'm asking to know if further PRs from the community to add them for terminal operators have a chance of getting merged.

[hfhbd]

Hey,
If I apply this patch and use a local object implementing SharedFlow:

interface Clock: SharedFlow<Int> { ... }
fun Clock() = object: Clock { }

the execution fails with KotlinNothingValueException before the second emit. Using an extra class class ClockImpl: Clock works without failing. Did you noticed this behavior too?

https://youtrack.jetbrains.com/issue/KT-48982

[dkhalanskyjb]

Looks good modulo some doc nits.

[qwwdfsad]

@LouisCAD to do :) Feel free to create a PR with additional overloads