Magnatune plugin improvements
This MR provides the following improvements to Magnatune plugin:
- display info bar to unlock keyring if not unlocked
- do no store or print sensitive userinfo subcomponent of uri
- add opus / alac / aac download formats
- launch date for first-seen column
- add 'View All' action to toolbar
- display album download size progress in task detail
- generate album download url from pre-defined format
- minor improvements to preferences and loading ui pages
- handle error cases slightly better
- force catalog download if previous catalog load was not successful
- fix issues with rb_error_dialog in python plugins