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>

services/gitdiff/git_diff_tree.go

@@ -61,7 +61,7 @@ func runGitDiffTree(ctx context.Context, gitRepo *git.Repository, useMergeBase b
 		cmd.AddArguments("--merge-base")
 	}
 	cmd.AddDynamicArguments(baseCommitID, headCommitID)
-	stdout, _, runErr := cmd.RunStdString(ctx, &gitcmd.RunOpts{Dir: gitRepo.Path})
+	stdout, _, runErr := cmd.WithDir(gitRepo.Path).RunStdString(ctx)
 	if runErr != nil {
 		log.Warn("git diff-tree: %v", runErr)
 		return nil, runErr

services/gitdiff/gitdiff.go

@@ -1170,12 +1170,11 @@ func getDiffBasic(ctx context.Context, gitRepo *git.Repository, opts *DiffOption
 
 	go func() {
 		stderr := &bytes.Buffer{}
-		if err := cmdDiff.Run(cmdCtx, &gitcmd.RunOpts{
-			Timeout: time.Duration(setting.Git.Timeout.Default) * time.Second,
-			Dir:     repoPath,
-			Stdout:  writer,
-			Stderr:  stderr,
-		}); err != nil && !git.IsErrCanceledOrKilled(err) {
+		if err := cmdDiff.WithTimeout(time.Duration(setting.Git.Timeout.Default) * time.Second).
+			WithDir(repoPath).
+			WithStdout(writer).
+			WithStderr(stderr).
+			Run(cmdCtx); err != nil && !git.IsErrCanceledOrKilled(err) {
 			log.Error("error during GetDiff(git diff dir: %s): %v, stderr: %s", repoPath, err, stderr.String())
 		}