[MODERATION] Add repo transfers to blocked functionality (squash)

- When someone gets blocked, remove all pending repository transfers
from the blocked user to the doer.
- Do not allow to start transferring repositories to the doer as blocked user.
- Added unit testing.
- Added integration testing.

(cherry picked from commit 8a3caac330)
(cherry picked from commit a92b4cfeb6)
(cherry picked from commit acaaaf07d9)
(cherry picked from commit 735818863c)

routers/web/repo/setting/setting.go

@@ -5,6 +5,7 @@
 package setting
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -775,7 +776,9 @@ func SettingsPost(ctx *context.Context) {
 		}
 
 		if err := repo_service.StartRepositoryTransfer(ctx, ctx.Doer, newOwner, repo, nil); err != nil {
-			if repo_model.IsErrRepoAlreadyExist(err) {
+			if errors.Is(err, user_model.ErrBlockedByUser) {
+				ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_blocked_doer"), tplSettingsOptions, nil)
+			} else if repo_model.IsErrRepoAlreadyExist(err) {
 				ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_has_same_repo"), tplSettingsOptions, nil)
 			} else if models.IsErrRepoTransferInProgress(err) {
 				ctx.RenderWithErr(ctx.Tr("repo.settings.transfer_in_progress"), tplSettingsOptions, nil)