🍒[5.9][Concurrency] Adopt stable keyword consuming instead of __owned

[ktoso]

Description:
This change is ABI stable with regards to the mangled name of the enqueue method.

We confirmed this by manually comparing mangled names of a method with __owned and later a consuming parameter -- please double check this though @kavon as you'd know more about this than myself.

This also improves diagnostics around implementing move-only job requirement, since the diagnostics offered by _owned are wrong: they don't show the attribute leading people to add func enqueue( job: ExecutorJob) which is incorrect because they MUST add consuming.

This PR includes tests that simulate an SDK with either the __owned or consuming versions and implementations with the other spelling, to make sure this works as expected.

Risk: Low, the mangling and ABI is the same.
Review by: @kavon @DougGregor
Testing: CI testing; manually verified mangling of the changed method
Original PR: #65571
Radar: rdar://108467550

[ktoso]

@swift-ci please test

[ktoso]

Depends on #65455 since that introduces new methods; so we want to do the same to the new ones IF we are to merge these new methods.

[ktoso]

@swift-ci please test

[ktoso]

Github is having issues; Exception: ['git', 'clone', '--recursive', 'https://github.com/apple/swift-docc.git', 'swift-docc'] checkouts failing

[ktoso]

@swift-ci please test

[kavon]

Just as a note:

This also improves diagnostics around implementing move-only job requirement, since the diagnostics offered by _owned are wrong: they don't show the attribute leading people to add func enqueue( job: ExecutorJob) which is incorrect because they MUST add consuming.

This isn't what the PR is improving. It's just using the consuming attribute rather than __owned, because the latter is confusing for people to see because it's not one of the official ownership specifiers (it's an old name for consuming). So this change is really about changing an API so it uses the better names for this. I don't think we're ever going to suggest people write __owned in a diagnostic.

[ktoso]

I mean this specifically was causing bad diagnostics telling people to implement "enqueue( job: ExecutorJob)" which then would not compile, since it was missing the __owned; Unless I'm misremembering this change also causes producing the right diagnostic.

[ktoso]

Thanks for review!