Merge branch 'tb/refs-exclusion-and-packed-refs'

Merge branch 'tb/refs-exclusion-and-packed-refs'

Enumerating refs in the packed-refs file, while excluding refs that
match certain patterns, has been optimized.

* tb/refs-exclusion-and-packed-refs:
  ls-refs.c: avoid enumerating hidden refs where possible
  upload-pack.c: avoid enumerating hidden refs where possible
  builtin/receive-pack.c: avoid enumerating hidden references
  refs.h: implement `hidden_refs_to_excludes()`
  refs.h: let `for_each_namespaced_ref()` take excluded patterns
  revision.h: store hidden refs in a `strvec`
  refs/packed-backend.c: add trace2 counters for jump list
  refs/packed-backend.c: implement jump lists to avoid excluded pattern(s)
  refs/packed-backend.c: refactor `find_reference_location()`
  refs: plumb `exclude_patterns` argument throughout
  builtin/for-each-ref.c: add `--exclude` option
  ref-filter.c: parameterize match functions over patterns
  ref-filter: add `ref_filter_clear()`
  ref-filter: clear reachable list pointers after freeing
  ref-filter.h: provide `REF_FILTER_INIT`
  refs.c: rename `ref_filter`