EDIT: To be done after #4677

This issue is part of the EPIC: Signature process of an initiative #4644

• Configure type of authorization required to sign an initiative, based on the available authorizations for the organization the initiative belongs to.
• The users with the corresponding authorization should be able to sign initiatives, otherwise they should see the button to sign an initiative in grey colour.

It seems that the Identity document authorization with DNI/NIF/Passport must be enabled in the organization to satisfy the security concerns:

• The DNI provided by the user is checked with the DNI hash created in the authorization process
• Once validated the DNI, it can be used to detect if an initiative has been already voted with another hash created from a concatenation including the DNI and the initiative identifier. In this way the users table and the votes table can't be related without the DNIs.

cc/ @decidim/product