Move RepoTransfer from models to models/repo sub package (#32506)

`RepoTransfer` now is at models, but if we want to move it into `repo`
model, it will depend on `Team`. So this PR also makes repo model depend
on org model to make it possible. Just refactor, no code change.

- [x] Move `DeleteOrganization` from `models/organization` to service
layer
- [x] Move `AccessibleTeamReposEnv` to `models/repo`
- [x] Move `RepoTransfer` from `models` to `models/repo`
- [x] Merge `getUserTeamIDs` and `GetUserTeamIDs`, Merge `GetUserTeams`
and `getUserTeams`.
- [x] Remove `Team`'s `Repos []*repo_model.Repository` to avoid dependency recycle.

routers/web/org/teams.go

@@ -410,11 +410,15 @@ func TeamRepositories(ctx *context.Context) {
 		return
 	}
 
-	if err := ctx.Org.Team.LoadRepositories(ctx); err != nil {
-		ctx.ServerError("GetRepositories", err)
+	repos, err := repo_model.GetTeamRepositories(ctx, &repo_model.SearchTeamRepoOptions{
+		TeamID: ctx.Org.Team.ID,
+	})
+	if err != nil {
+		ctx.ServerError("GetTeamRepositories", err)
 		return
 	}
 	ctx.Data["Units"] = unit_model.Units
+	ctx.Data["TeamRepos"] = repos
 	ctx.HTML(http.StatusOK, tplTeamRepositories)
 }