Fix tags sort by creation time (descending) on branch/tag dropdowns (#23491)

This PR fixes the tags sort issue mentioned in #23432
The tags on dropdown shoud be sorted in descending order of time but are
not. Because when getting tags, it execeutes `git tag sort
--sort=-taggerdate`. Git supports two types of tags: lightweight and
annotated, and `git tag sort --sort=-taggerdate` dosen't work with
lightweight tags, which will not give correct result. This PR add
`GetTagNamesByRepoID ` to get tags from the database so the tags are
sorted.

Also adapt this change to the droplist when comparing branches. 

Dropdown places:

<img width="369" alt="截屏2023-03-15 14 25 39"
src="https://user-images.githubusercontent.com/17645053/225224506-65a72e50-4c11-41d7-8187-a7e9c7dab2cb.png">

<img width="675" alt="截屏2023-03-15 14 25 27"
src="https://user-images.githubusercontent.com/17645053/225224526-65ce8008-340c-43f6-aa65-b6bd9e1a1bf1.png">

modules/context/repo.go

@@ -660,20 +660,9 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 		return
 	}
 
-	tags, err := ctx.Repo.GitRepo.GetTags(0, 0)
+	tags, err := repo_model.GetTagNamesByRepoID(ctx, ctx.Repo.Repository.ID)
 	if err != nil {
-		if strings.Contains(err.Error(), "fatal: not a git repository ") {
-			log.Error("Repository %-v has a broken repository on the file system: %s Error: %v", ctx.Repo.Repository, ctx.Repo.Repository.RepoPath(), err)
-			ctx.Repo.Repository.Status = repo_model.RepositoryBroken
-			ctx.Repo.Repository.IsEmpty = true
-			ctx.Data["BranchName"] = ctx.Repo.Repository.DefaultBranch
-			// Only allow access to base of repo or settings
-			if !isHomeOrSettings {
-				ctx.Redirect(ctx.Repo.RepoLink)
-			}
-			return
-		}
-		ctx.ServerError("GetTags", err)
+		ctx.ServerError("GetTagNamesByRepoID", err)
 		return
 	}
 	ctx.Data["Tags"] = tags