Provide test address books via DI

[sunkup]

Purpose

At the moment test address books are provided via a static companion object method which requires context to be passed in. Passing context to static methods is an antipattern, since the global accessibility of context introduces testing issues and hinders maintainability.

Short description

• Create LocalTestAddressBookProvider which can be injected in test classes to provide LocalTestAddressBooks
• Provide and use test address books in a "provide" method which ensures we always start with a clean slate. It deletes any old testing address books before creating the new testing address book which it cleans beforehand (removes contacts).
• Move dirty check methods from LocalTestAddressBook to LocalGroupTest, since that's the only place they are used
• remove unused readOnly flag

Note: We should probably not completely remove LocalTestAddressBook since it still gives us an easy way to set the group method for tests - which is a valid use case in my eyes. I don't think using a LocalAddressBook interface or mocking all the group method calls just to get rid of LocalTestAddressBook are very beneficial.

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.

[ArnyminerZ]

Looks good to me

[rfc2822]

But very nice 👍🏻

[rfc2822]

Minor things

[rfc2822]

Nice 👍🏻😃