ADL-proof implementation of function, move_only_function, packaged_task, promise, and optional

[frederick-vs-ja]

Towards #140 and #3100.

Unblocks one libcxx test:

• std/utilities/function.objects/func.wrap/func.wrap.func/robust_against_adl.pass.cpp

Also contains some drive-by and previously missed changes.

• Handling for array destruction in algorithms (valid since C++20) was missed in ADL-proof implementation of uninitialized memory algorithms #4374.
• _STD-qualification for one shared_ptr-related _Unfancy call (which is not strictly necessary).
• _STD-qualification for _Deallocate and _Make_unique_alloc calls (which are not strictly necessary IIUC).
• Moving _Global_new from <xmemory> to <functional> because it is only used for function.

Remaining unqualified _Construct_in_place and _Destroy_in_place calls after this PR are all in containers and valarray.

[AlexGuteniev]

Is move_only_function affected at all?

[frederick-vs-ja]

Is move_only_function affected at all?

Yes. The _Function_new_large call used for move_only_function needs to be qualified.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks for fixing another libcxx failure and qualifying all the things! 🛠️ 📈 🎉