Add chapter deduplication filter

[MagicfTail]

This pull requests implements source de-duplication, adding the ability to hide duplicate chapters, by only showing the chapter from the preferred source. The filter option also affects the library view, correctly showing how many actual unread chapters are available when de-duplication is enabled.
The preferred source can be configured, and is based on the order of the selected sources. If no source is set as preferred, the source will be selected alphabetically.
Example showcase:
example

In order to facilitate this, the LibraryView view is modified, and a new table is added to the database.

Checklist:

• The selected sorted sources are saved/restored on backup.
• Merged manga is correctly supported
• The filter interfaces correctly with existing filters
• UI text is stored as resources and can be translated

Implements #1419

[jobobby04]

Hmm, so this is a ranking system 🤔
I'll take a more in-depth look when I can

[MagicfTail]

Hmm, so this is a ranking system 🤔 I'll take a more in-depth look when I can

Naming is not my strong suite 😅
I'm more than open to a rename if you think something else is more clear.