[entropy.client.client] add installed packages repository locking support
[entropy.client.dep] add installed packages repository locking support
[entropy.client.db] add installed packages repository locking support
[entropy.client.repository] do not check the instance type of installed_repository

This check is no longer needed
[entropy.client.repository] drop entropy_updates_alert argument

This is no longer useful for the implemented use cases
[entropy.client.methods] add installed packages repository locking support
[entropy.client.settings] add installed packages repository locking support