refactor(backend): typescript for activity pub

Created by: ulfgebhardt

🍰 Pullrequest

typescript for activity pub.

Since the code is not in use the potential breakage is near zero. The quality of the code is very bad in this particular section - i chose to keep the code and make minimal changes to have it running with the ts.

Issues

• based on https://github.com/Ocelot-Social-Community/Ocelot-Social/pull/6390

Todo

• None