Refactor git command arguments and make all arguments to be safe to be used (#21535)

Follow #21464

Make all git command arguments strictly safe. Most changes are one-to-one replacing, keep all existing logic.

services/gitdiff/gitdiff_test.go

@@ -627,7 +627,7 @@ func TestGetDiffRangeWithWhitespaceBehavior(t *testing.T) {
 		return
 	}
 	defer gitRepo.Close()
-	for _, behavior := range []string{"-w", "--ignore-space-at-eol", "-b", ""} {
+	for _, behavior := range []git.CmdArg{"-w", "--ignore-space-at-eol", "-b", ""} {
 		diffs, err := GetDiff(gitRepo,
 			&DiffOptions{
 				AfterCommitID:      "bd7063cc7c04689c4d082183d32a604ed27a24f9",