fix(repository): Move backend code into subdirectory

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/media/media-backend.interface.ts

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { BackendData } from './media-upload.entity';
+
+export interface MediaBackend {
+  /**
+   * Saves a file according to backend internals.
+   * @param buffer File data
+   * @param fileName Name of the file to save. Can include a file extension.
+   * @throws {MediaBackendError} - there was an error saving the file
+   * @return Tuple of file URL and internal backend data, which should be saved.
+   */
+  saveFile(buffer: Buffer, fileName: string): Promise<[string, BackendData]>;
+
+  /**
+   * Delete a file from the backend
+   * @param fileName String to identify the file
+   * @param backendData Internal backend data
+   * @throws {MediaBackendError} - there was an error deleting the file
+   */
+  deleteFile(fileName: string, backendData: BackendData): Promise<void>;
+}