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.

models/activities/action.go

@@ -511,7 +511,7 @@ func ActivityQueryCondition(ctx context.Context, opts GetFeedsOptions) (builder.
 	}
 
 	if opts.RequestedTeam != nil {
-		env := organization.OrgFromUser(opts.RequestedUser).AccessibleTeamReposEnv(ctx, opts.RequestedTeam)
+		env := repo_model.AccessibleTeamReposEnv(ctx, organization.OrgFromUser(opts.RequestedUser), opts.RequestedTeam)
 		teamRepoIDs, err := env.RepoIDs(1, opts.RequestedUser.NumRepos)
 		if err != nil {
 			return nil, fmt.Errorf("GetTeamRepositories: %w", err)