* Add messages informing that collections are empty

Adds empty messages to blocked users, domain blocks, favourited statuses, users
that favourited toot, follow requests, followers of given user, user's being
followed by given user, lists, muted users, toots' boosts.

Switched from using ScrollContainer to ScrollableList and/or added empty
message's text.

Fixes #4115

* Update localization files with strings for #4115

* Fix whitespace issues pointed out by codeclimate