refactor: make git package handle all git operations (#38543)

before: gitrepo vs git packages
after: git package fully handle all git operations

by the way, use `WithRepo(repo)` instead of `WithDir(repo.Path)` to hide
path details.

benefits:

1. remove all unnecessary wrappers, developers no need to struggle with
"which package should be used"
2. simplify code, RepositoryFacade can (will) be used everywhere, all
"path" details are (will be) hidden

services/pull/update.go

@@ -14,7 +14,7 @@ import (
 	repo_model "gitea.dev/models/repo"
 	"gitea.dev/models/unit"
 	user_model "gitea.dev/models/user"
-	"gitea.dev/modules/gitrepo"
+	"gitea.dev/modules/git"
 	"gitea.dev/modules/globallock"
 	"gitea.dev/modules/log"
 	"gitea.dev/modules/repository"
@@ -41,7 +41,7 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 
 	// TODO: FakePR: if the PR is a fake PR (for example: from Merge Upstream), then no need to check diverging
 	if pr.ID > 0 {
-		diffCount, err := gitrepo.GetDivergingCommits(ctx, pr.BaseRepo, pr.BaseBranch, pr.GetGitHeadRefName())
+		diffCount, err := git.GetDivergingCommits(ctx, pr.BaseRepo, pr.BaseBranch, pr.GetGitHeadRefName())
 		if err != nil {
 			return err
 		} else if diffCount.Behind == 0 {
@@ -213,7 +213,7 @@ func syncCommitDivergence(ctx context.Context, pr *issues_model.PullRequest) err
 	if err := pr.LoadBaseRepo(ctx); err != nil {
 		return err
 	}
-	divergence, err := gitrepo.GetDivergingCommits(ctx, pr.BaseRepo, pr.BaseBranch, pr.GetGitHeadRefName())
+	divergence, err := git.GetDivergingCommits(ctx, pr.BaseRepo, pr.BaseBranch, pr.GetGitHeadRefName())
 	if err != nil {
 		return err
 	}