LocalAddressBook: move contacts when renaming the address book account

[rfc2822]

Purpose

Previously, renaming an address book (= address book account) resulted in all local contacts being dropped and re-synced.

However, contacts (and groups) should be kept when an address book account is renamed so that there are as little possibilities for errors as possible. For instance, at re-sync the server could be not available or there could be (temporary) problems with specific contacts which would not appear without re-sync etc.

Short description

Instead of renaming the account with AccountManager.renameAccount():

1. a new account with the desired name is created,
2. the contacts and groups are moved to the new account (without touching their dirty flag),
3. the old account is deleted.

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.