[PATCH 0/7] MR1629: ntdll: Finish heap refactoring in preparation for LFH support.

[Rémi Bernon (＠rbernon)]

Cleaning up and splitting subheap creation helpers and free block merge logic.

Should be the last refactoring needed before LFH specific changes, as implemented in https://gitlab.winehq.org/wine/wine/-/merge_requests/1628.