feat: reverse shares (#86)

* add first concept

* add reverse share funcionality to frontend

* allow creator to limit share expiration

* moved reverse share in seperate module

* add table to manage reverse shares

* delete complete share if reverse share was deleted

* optimize function names

* add db migration

* enable reverse share email notifications

* fix config variable descriptions

* fix migration for new installations

backend/src/reverseShare/reverseShare.module.ts

@@ -0,0 +1,12 @@
+import { forwardRef, Module } from "@nestjs/common";
+import { FileModule } from "src/file/file.module";
+import { ReverseShareController } from "./reverseShare.controller";
+import { ReverseShareService } from "./reverseShare.service";
+
+@Module({
+  imports: [forwardRef(() => FileModule)],
+  controllers: [ReverseShareController],
+  providers: [ReverseShareService],
+  exports: [ReverseShareService],
+})
+export class ReverseShareModule {}