The user can now authenticate with the authorization
server's authorization endpoint and receive a fake
id token.

Client must now be registered prior to imitating a
call to the token endpoint with the password flow.

Squashed commits:

[fdcef62] Rename authorization endpoint to protected resource endpoint

closes #6603

closes #6587

Fix a security issue that author_signature is not checked on the to-downstream receive of a federated relayable entity, allowing to forge relayables if you are an owner of the pod where a parent object is stored.

closes #6539

These are some initial tests, more to come.

It tests some features of Request, StatusMessage, Comment, Like,
Participation, Retraction, SignedRetraction, RelayableRetraction entities
receive process.

closes #6573

When author of the root post receives a reshare to it, no participation is added to the root author on the reshare. This causes any comments on the reshare on remote pods not to be sent to the author. Adding a participation should subscribe to the reshare and thus bring added comments back to the author.

closes #6481

As posts are always delivered also to reshare root, comments should also be delivered to reshare root, for concistency.

Do not add participation for comment if comment validation failed The same fix is also done for the other social actions

closes #6552

Fixes #5485

closes #6533

closes #6512

closes #6503

closes #6499

closes #6496

closes #6490