I tripped over this function while trying to run a game, so I thought I would have a go at it :-)
The implementation is very similar to what is done in `Local32Info16` already.
Regarding the place to put the function: I am not sure about the exact relationship between `kernel32` and `kernelbase`, but as most of the heap related functions are implemented in `kernelbase` I opted to add it to the latter. The tests reside in the `kernel32` directory though.
The tests are currently pretty basic as I was a bit hesitant to compare against hard coded sizes for reserved / committed memory (that could break if someone made changes to the heap implementation).
Also, I am not entirely sure about the semantics of the `cbMaxReserve` field. I opted to always set it to the same value as `cbReserved`, which seems *good enough™*.
Let me know if this needs improvement!
-- v5: kernelbase: Implement HeapSummary