Merge branch 'en/header-split-cache-h-part-3' into next

Header files cleanup.

Kicked out of 'next', applied build fixes including js/cmake-wo-cache-h

* en/header-split-cache-h-part-3: (28 commits)
  fsmonitor-ll.h: split this header out of fsmonitor.h
  hash-ll, hashmap: move oidhash() to hash-ll
  object-store-ll.h: split this header out of object-store.h
  khash: name the structs that khash declares
  merge-ll: rename from ll-merge
  git-compat-util.h: remove unneccessary include of wildmatch.h
  builtin.h: remove unneccessary includes
  list-objects-filter-options.h: remove unneccessary include
  diff.h: remove unnecessary include of oidset.h
  repository: remove unnecessary include of path.h
  log-tree: replace include of revision.h with simple forward declaration
  cache.h: remove this no-longer-used header
  read-cache*.h: move declarations for read-cache.c functions from cache.h
  repository.h: move declaration of the_index from cache.h
  merge.h: move declarations for merge.c from cache.h
  diff.h: move declaration for global in diff.c from cache.h
  preload-index.h: move declarations for preload-index.c from elsewhere
  sparse-index.h: move declarations for sparse-index.c from cache.h
  name-hash.h: move declarations for name-hash.c from cache.h
  run-command.h: move declarations for run-command.c from cache.h
  ...

Documentation/CodingGuidelines

@@ -448,7 +448,7 @@ For C programs:
  - The first #include in C files, except in platform specific compat/
    implementations and sha1dc/, must be either "git-compat-util.h" or
    one of the approved headers that includes it first for you.  (The
-   approved headers currently include "cache.h", "builtin.h",
+   approved headers currently include "builtin.h",
    "t/helper/test-tool.h", "xdiff/xinclude.h", or
    "reftable/system.h").  You do not have to include more than one of
    these.