Add a simple way to rename branch like gh (#15870)

- Update default branch if needed
- Update protected branch if needed
- Update all not merged pull request base branch name
- Rename git branch
- Record this rename work and auto redirect for old branch on ui

Signed-off-by: a1012112796 <1012112796@qq.com>
Co-authored-by: delvh <dev.lh@web.de>

modules/git/repo_branch.go

@@ -164,3 +164,9 @@ func (repo *Repository) RemoveRemote(name string) error {
 func (branch *Branch) GetCommit() (*Commit, error) {
 	return branch.gitRepo.GetBranchCommit(branch.Name)
 }
+
+// RenameBranch rename a branch
+func (repo *Repository) RenameBranch(from, to string) error {
+	_, err := NewCommand("branch", "-m", from, to).RunInDir(repo.Path)
+	return err
+}