Move some functions to gitrepo package (#35543)

Refactor Git command functions to use WithXXX methods instead of
exposing RunOpts.
This change simplifies reuse across gitrepo and improves consistency,
encapsulation, and maintainability of command options.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/integration/git_lfs_ssh_test.go

@@ -45,7 +45,9 @@ func TestGitLFSSSH(t *testing.T) {
 			setting.LFS.AllowPureSSH = true
 			require.NoError(t, cfg.Save())
 
-			_, _, cmdErr := gitcmd.NewCommand("config", "lfs.sshtransfer", "always").RunStdString(t.Context(), &gitcmd.RunOpts{Dir: dstPath})
+			_, _, cmdErr := gitcmd.NewCommand("config", "lfs.sshtransfer", "always").
+				WithDir(dstPath).
+				RunStdString(t.Context())
 			assert.NoError(t, cmdErr)
 			lfsCommitAndPushTest(t, dstPath, 10)
 		})