Report operator new[] allocations as a distinct type in heap profiles.

[copybara-service]

Report operator new[] allocations as a distinct type in heap profiles.

Sampled heap profiles label each sample with the family of the allocation
function it came from ("new", "malloc", "aligned malloc"). operator new[]
showed up as "new" because the array operators were symbol aliases of the
scalar ones. That misleads tools which infer the allocated type by matching
a sample's requested size against sizeof(T) of the candidates on its call
stack: an array requests n * sizeof(T), plus an array cookie for some types,
so it rarely matches the single object the stack suggests.

Distinguish the two with a compile-time array sub-policy of TCMallocPolicy
and give the array entry points (the global operators, the
TCMallocInternalNewArray* functions, and the _alloc_token__Znam entry
points used by heap partitioning) bodies of their own, so that sampled
stacks record AllocationType::NewArray and profiles label them "new[]".

Beyond the label, behavior is unchanged: new[] keeps the size-class
partition of scalar new, the delete operators stay aliased, and mismatch
detection still accepts new[]/delete[] exactly as it accepts new/delete.
The policy difference is resolved at compile time, so the non-sampled fast
path is the same code, only instantiated a few more times. operator new[]
does, however, no longer share an address with operator new, which the
alias test used to assert.

The nothrow array alloc-token declaration gains the noexcept of its scalar
counterpart, which its definition now requires.

ProfileTest.HeapProfile is skipped in builds with alloc-token
instrumentation, so a heap_profiling_test case checks the type reported for
new and new[] expressions as the compiler actually emits them.

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