irmin: expose info type equality

[samoht]

That allows to re-use the same info function in various store - in practice backend are either using Irmin.Info.default or Imin_unix.info so it's a bit odd to hide that equality.

[codecov-commenter]

Codecov Report

Merging #2189 (cb6cd7c) into main (e68f6a7) will increase coverage by 0.04%. The diff coverage is 87.50%.

:exclamation: Current head cb6cd7c differs from pull request most recent head 7c6a1c3. Consider uploading reports for the commit 7c6a1c3 to get more accurate results

:mega: This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@            Coverage Diff             @@
##             main    #2189      +/-   ##
==========================================
+ Coverage   68.09%   68.13%   +0.04%     
==========================================
  Files         135      135              
  Lines       16222    16255      +33     
==========================================
+ Hits        11046    11075      +29     
- Misses       5176     5180       +4     

Impacted Files	Coverage Δ
src/irmin-git/irmin_git.ml	45.45% <ø> (ø)
src/irmin-pack/unix/file_manager.ml	84.12% <ø> (ø)
src/irmin/irmin.ml	95.00% <ø> (ø)
src/irmin-pack/version.ml	44.82% <20.00%> (+0.38%)	:arrow_up:
src/irmin-pack/unix/control_file.ml	91.52% <91.80%> (+1.20%)	:arrow_up:
src/irmin-pack/unix/control_file_intf.ml	95.45% <100.00%> (-4.55%)	:arrow_down:
src/irmin-test/store.ml	94.89% <0.00%> (-0.06%)	:arrow_down:
src/irmin-fs/unix/irmin_fs_unix.ml	68.38% <0.00%> (ø)

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more

[samoht]

Rebased