Implement forgetting about rooms (#1572)

* Add basic storage methods

* Add internal api handler

* Add check for forgotten room

* Add /rooms/{roomID}/forget endpoint

* Add missing rsAPI method

* Remove unused parameters

* Add passing tests

Signed-off-by: Till Faelligen <tfaelligen@gmail.com>

* Add missing file

* Add postgres migration

* Add sqlite migration

* Use Forgetter to forget room

* Remove empty line

* Update HTTP status codes

It looks like the spec calls for these to be 400, rather than 403: https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-rooms-roomid-forget

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

roomserver/storage/postgres/deltas/20201028212440_add_forgotten_column.go

@@ -0,0 +1,47 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package deltas
+
+import (
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/pressly/goose"
+)
+
+func LoadFromGoose() {
+	goose.AddMigration(UpAddForgottenColumn, DownAddForgottenColumn)
+}
+
+func LoadAddForgottenColumn(m *sqlutil.Migrations) {
+	m.AddMigration(UpAddForgottenColumn, DownAddForgottenColumn)
+}
+
+func UpAddForgottenColumn(tx *sql.Tx) error {
+	_, err := tx.Exec(`ALTER TABLE roomserver_membership ADD COLUMN IF NOT EXISTS forgotten BOOLEAN NOT NULL DEFAULT false;`)
+	if err != nil {
+		return fmt.Errorf("failed to execute upgrade: %w", err)
+	}
+	return nil
+}
+
+func DownAddForgottenColumn(tx *sql.Tx) error {
+	_, err := tx.Exec(`ALTER TABLE roomserver_membership DROP COLUMN IF EXISTS forgotten;`)
+	if err != nil {
+		return fmt.Errorf("failed to execute downgrade: %w", err)
+	}
+	return nil
+}