Sync branches into databases (#22743)

Related #14180
Related #25233 
Related #22639
Close #19786
Related #12763 

This PR will change all the branches retrieve method from reading git
data to read database to reduce git read operations.

- [x] Sync git branches information into database when push git data
- [x] Create a new table `Branch`, merge some columns of `DeletedBranch`
into `Branch` table and drop the table `DeletedBranch`.
- [x] Read `Branch` table when visit `code` -> `branch` page
- [x] Read `Branch` table when list branch names in `code` page dropdown
- [x] Read `Branch` table when list git ref compare page
- [x] Provide a button in admin page to manually sync all branches.
- [x] Sync branches if repository is not empty but database branches are
empty when visiting pages with branches list
- [x] Use `commit_time desc` as the default FindBranch order by to keep
consistent as before and deleted branches will be always at the end.

---------

Co-authored-by: Jason Song <i@wolfogre.com>

services/pull/pull.go

@@ -170,7 +170,7 @@ func ChangeTargetBranch(ctx context.Context, pr *issues_model.PullRequest, doer
 		return err
 	}
 	if branchesEqual {
-		return models.ErrBranchesEqual{
+		return git_model.ErrBranchesEqual{
 			HeadBranchName: pr.HeadBranch,
 			BaseBranchName: targetBranch,
 		}
@@ -338,7 +338,7 @@ func AddTestPullRequestTask(doer *user_model.User, repoID int64, branch string,
 		for _, pr := range prs {
 			divergence, err := GetDiverging(ctx, pr)
 			if err != nil {
-				if models.IsErrBranchDoesNotExist(err) && !git.IsBranchExist(ctx, pr.HeadRepo.RepoPath(), pr.HeadBranch) {
+				if git_model.IsErrBranchNotExist(err) && !git.IsBranchExist(ctx, pr.HeadRepo.RepoPath(), pr.HeadBranch) {
 					log.Warn("Cannot test PR %s/%d: head_branch %s no longer exists", pr.BaseRepo.Name, pr.IssueID, pr.HeadBranch)
 				} else {
 					log.Error("GetDiverging: %v", err)