ICRC-25: Split out identity information from `icrc25_request_permission` method

[frederikrothenberger]

This PR splits the identitiy information part of the existing icrc25_request_permission method into another method called icrc25_get_identities. This makes the methods more focused.

The PR also adds clarifying information about how user interaction should be handled for the given methods. In particular, it allows signers to skip user interaction if the user previously approved the same request.

[frederikrothenberger]

I guess I'm missing something, but previously it was clear that the permission (e.g. for the scope icrc25_canister_call) is issued for the identities included in the response. With the current change, when we have two separate calls, it is not clear which identities are meant for which permissions. Maybe add an example with a typical interplay of the scopes? Or maybe we can discuss it next week?

The selection of identities and the permission scopes granted are orthogonal. This was also the case previously, but making it two separate calls makes this more explicit.

Both, identities and permission scopes are selected / granted for a specific session. And both of these things can change independently over the lifetime of that session.

I.e.:

• previously granted permission scopes can be revoked without changing the identities shared with the RP
• the list of identities shared with the RP can be adjusted during the session without changing permission scopes