Merge branch 'master' into ds/backfill

* master: (446 commits)
  The seventh batch
  The sixth batch
  The fifth batch
  The fourth batch
  refs/reftable: fix uninitialized memory access of `max_index`
  remote: announce removal of "branches/" and "remotes/"
  The third batch
  hash.h: drop unsafe_ function variants
  csum-file: introduce hashfile_checkpoint_init()
  t/helper/test-hash.c: use unsafe_hash_algo()
  csum-file.c: use unsafe_hash_algo()
  hash.h: introduce `unsafe_hash_algo()`
  csum-file.c: extract algop from hashfile_checksum_valid()
  csum-file: store the hash algorithm as a struct field
  t/helper/test-tool: implement sha1-unsafe helper
  trace2: prevent segfault on config collection with valueless true
  refs: fix creation of reflog entries for symrefs
  ci: wire up Visual Studio build with Meson
  ci: raise error when Meson generates warnings
  meson: fix compilation with Visual Studio
  ...