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

frontend/src/types/share.type.ts

@@ -26,6 +26,13 @@ export type MyShare = Share & {
   cratedAt: Date;
 };
 
+export type MyReverseShare = {
+  id: string;
+  maxShareSize: string;
+  shareExpiration: Date;
+  share?: MyShare;
+};
+
 export type ShareSecurity = {
   maxViews?: number;
   password?: string;