nonmoving: Add support for heap profiling

This MR adds support for heap profiling with the non-moving collector.

We make use of the recently added concurrent collection flag to ensure that, when heap profiling, all nonmoving collections are non-concurrent. This makes the heap census logic much simpler, since we don't need to worry about allocations during the non-moving collection.

Another thing to note is that we follow the behaviour of live bytes accounting in using the segment block size as the size of heap objects on the non-moving heap.

Resolves #22221 (closed)