Get manga info from tracker

[NGB-Was-Taken]

Allows setting manga info to the one provided by tracker (currently includes title, author, artist, thumbnail url and description).

Closes #1205

TODO:

• Implement for all trackers.
• Properly handle multiple trackers.
• Handle rate-limits and other HttpExceptions (hoping a single try catch is enough)
• Automatically fetch metadata when tracker is added to an entry for the first time (?)
• Replace strings with moko strings.

[NGB-Was-Taken]

Automatically fetch metadata when tracker is added to an entry for the first time

Where should I do this and how do I update the manga info from there?