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/app.module.ts

@@ -13,6 +13,7 @@ import { PrismaModule } from "./prisma/prisma.module";
 import { ShareModule } from "./share/share.module";
 import { UserModule } from "./user/user.module";
 import { ClamScanModule } from "./clamscan/clamscan.module";
+import { ReverseShareModule } from "./reverseShare/reverseShare.module";
 
 @Module({
   imports: [
@@ -30,6 +31,7 @@ import { ClamScanModule } from "./clamscan/clamscan.module";
     }),
     ScheduleModule.forRoot(),
     ClamScanModule,
+    ReverseShareModule,
   ],
   providers: [
     {