fix(repository): Move backend code into subdirectory

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

backend/src/revisions/edit.service.ts

@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { Injectable } from '@nestjs/common';
+
+import { EditDto } from './edit.dto';
+import { Edit } from './edit.entity';
+
+@Injectable()
+export class EditService {
+  async toEditDto(edit: Edit): Promise<EditDto> {
+    const authorUser = await (await edit.author).user;
+
+    return {
+      username: authorUser ? authorUser.username : null,
+      startPos: edit.startPos,
+      endPos: edit.endPos,
+      createdAt: edit.createdAt,
+      updatedAt: edit.updatedAt,
+    };
+  }
+}