Trigger event core\event\role_capabilities_updated inside of assign_capability()

At the moment event core\event\role_capabilities_updated is triggered after calling to assign_capability()

First benefit will be that we will event/log particular changes instead of general "some permissions changed"

Second benefit is that we will event/log ALL situations where capabilities are changed which are not logged atm such as:

• adding/removing individual capabilities (non-advanced mode)
• capabilities overrides restored from backup file
• resetting capabilities