Merge branch 'ds/commit-graph-write-refactor'

Renamed from commit-graph-format-v2 and changed scope.

* ds/commit-graph-write-refactor:
  commit-graph: extract write_commit_graph_file()
  commit-graph: extract copy_oids_to_commits()
  commit-graph: extract count_distinct_commits()
  commit-graph: extract fill_oids_from_all_packs()
  commit-graph: extract fill_oids_from_commit_hex()
  commit-graph: extract fill_oids_from_packs()
  commit-graph: create write_commit_graph_context
  commit-graph: remove Future Work section
  commit-graph: collapse parameters into flags
  commit-graph: return with errors during write
  commit-graph: fix the_repository reference

diff --cc builtin/commit.c
Simple merge

diff --cc builtin/gc.c
Simple merge

diff --cc commit-graph.c
Simple merge

diff --cc commit.c
Simple merge

diff --cc t/t5318-commit-graph.sh
Simple merge