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.

tests/integration/api_user_block_test.go

@@ -8,7 +8,6 @@ import (
 	"net/http"
 	"testing"
 
-	"code.gitea.io/gitea/models"
 	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/db"
 	issues_model "code.gitea.io/gitea/models/issues"
@@ -42,7 +41,7 @@ func TestBlockUser(t *testing.T) {
 	}
 
 	countRepositoryTransfers := func(t *testing.T, senderID, recipientID int64) int64 {
-		transfers, err := models.GetPendingRepositoryTransfers(db.DefaultContext, &models.PendingRepositoryTransferOptions{
+		transfers, err := repo_model.GetPendingRepositoryTransfers(db.DefaultContext, &repo_model.PendingRepositoryTransferOptions{
 			SenderID:    senderID,
 			RecipientID: recipientID,
 		})