Respect address book permissions in the contacts app #3848

Initial Checklist

• I understand this is a user story and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

Part of #3844

User Story

As a user with access to a read-only address book, I want the UI to reflect my permissions so that I don't run into errors when trying to change contacts.

User Value

Address books can be shared or provided read-only. Offering create, edit or delete actions there leads to server errors the user can't understand.

Acceptance Criteria

• In address books without mayWrite, the "New" button, "Edit" and "Delete" are hidden or disabled with an explanation
• The details view indicates that the contact is read-only
• Unit tests cover both writable and read-only address books