[MODERATION] add user blocking API

- Follow up for: #540, #802
- Add API routes for user blocking from user and organization
perspective.
- The new routes have integration testing.
- The new model functions have unit tests.
- Actually quite boring to write and to read this pull request.

(cherry picked from commit f3afaf15c7)
(cherry picked from commit 6d754db3e5)
(cherry picked from commit d0fc8bc9d3)
(cherry picked from commit 9a53b0d1a0)
(cherry picked from commit 44a2a4fd48)
(cherry picked from commit 182025db9c)
(cherry picked from commit 558a35963e)

models/user/block.go

@@ -52,18 +52,29 @@ func UnblockUser(ctx context.Context, userID, blockID int64) error {
 	return err
 }
 
+// CountBlockedUsers returns the number of users the user has blocked.
+func CountBlockedUsers(ctx context.Context, userID int64) (int64, error) {
+	return db.GetEngine(ctx).Where("user_id=?", userID).Count(&BlockedUser{})
+}
+
 // ListBlockedUsers returns the users that the user has blocked.
 // The created_unix field of the user struct is overridden by the creation_unix
 // field of blockeduser.
-func ListBlockedUsers(ctx context.Context, userID int64) ([]*User, error) {
-	users := make([]*User, 0, 8)
-	err := db.GetEngine(ctx).
+func ListBlockedUsers(ctx context.Context, userID int64, opts db.ListOptions) ([]*User, error) {
+	sess := db.GetEngine(ctx).
 		Select("`forgejo_blocked_user`.created_unix, `user`.*").
 		Join("INNER", "forgejo_blocked_user", "`user`.id=`forgejo_blocked_user`.block_id").
-		Where("`forgejo_blocked_user`.user_id=?", userID).
-		Find(&users)
+		Where("`forgejo_blocked_user`.user_id=?", userID)
 
-	return users, err
+	if opts.Page > 0 {
+		sess = db.SetSessionPagination(sess, &opts)
+		users := make([]*User, 0, opts.PageSize)
+
+		return users, sess.Find(&users)
+	}
+
+	users := make([]*User, 0, 8)
+	return users, sess.Find(&users)
 }
 
 // ListBlockedByUsersID returns the ids of the users that blocked the user.