Merge branch 'en/header-split-cache-h-part-2'

Merge branch 'en/header-split-cache-h-part-2'

More header clean-up.

* en/header-split-cache-h-part-2: (22 commits)
  reftable: ensure git-compat-util.h is the first (indirect) include
  diff.h: reduce unnecessary includes
  object-store.h: reduce unnecessary includes
  commit.h: reduce unnecessary includes
  fsmonitor: reduce includes of cache.h
  cache.h: remove unnecessary headers
  treewide: remove cache.h inclusion due to previous changes
  cache,tree: move basic name compare functions from read-cache to tree
  cache,tree: move cmp_cache_name_compare from tree.[ch] to read-cache.c
  hash-ll.h: split out of hash.h to remove dependency on repository.h
  tree-diff.c: move S_DIFFTREE_IFXMIN_NEQ define from cache.h
  dir.h: move DTYPE defines from cache.h
  versioncmp.h: move declarations for versioncmp.c functions from cache.h
  ws.h: move declarations for ws.c functions from cache.h
  match-trees.h: move declarations for match-trees.c functions from cache.h
  pkt-line.h: move declarations for pkt-line.c functions from cache.h
  base85.h: move declarations for base85.c functions from cache.h
  copy.h: move declarations for copy.c functions from cache.h
  server-info.h: move declarations for server-info.c functions from cache.h
  packfile.h: move pack_window and pack_entry from cache.h
  ...