See https://codeberg.org/forgejo/discussions/issues/164 for the
rationale and discussion of this change.
Everything related to the `go-git` dependency is dropped (Only a single
instance is left in a test file to test for an XSS, it requires crafting
an commit that Git itself refuses to craft). `_gogit` files have
been removed entirely, `go:build: !gogit` is removed, `XXX_nogogit.go` files
either have been renamed or had their code being merged into the
`XXX.go` file.
Most time, when invoking `git.OpenRepository`, `objectFormat` will not
be used, so it's a waste to invoke commandline to get the object format.
This PR make it a lazy operation, only invoke that when necessary.
(cherry picked from commit e84e5db6de0306d514b1f1a9657931fb7197a188)
The test suite was broken e.g. on Debian 12 due to requiring a very
recent version of Git installed on the system. This commit skips SHA256
tests in the git module, if a Git version older than 2.42 or gogit is used.
