Manage repos with separate name and URL fields

[HebaruSan]

Problems

The repo and auth token sections of the GUI Settings use pipe characters to fake multiple columns:

The popup to add a repo:

• has title "Settings"
• is enormous compared to how much space its content requires
• isn't resizable
• also uses pipe characters to fake multiple columns in the list
• requires the user to type pipe characters in a special format to enter a custom repo
• has no label for its text field
• has the text field, cancel, and OK buttons inside the "Official repositories" frame even though these controls are not related to official repositories

Changes

• The repo table in Settings is a ListView with two columns
• The auth token table in Settings is a ListView with two columns

• Title is now "Add Repository"
• The blank space in the repo list is reduced
• The form is resiable
• The list is now a ListView with two columns
• The text box is split into one for name, one for URL, each with a label, so the user doesn't have to type pipes
• The text box and buttons are moved outside the "Official repositories" frame
• The "OK" button is now relabeled to the more descriptive "Add" and is the same width as the other button, and they have keyboard shortcuts

[DasSkelett]

I've just pushed a small fix for the auth token section, we used to disable the DeleteRepoButton instead of the DeleteAuthTokenButton there.

[DasSkelett]

Improved usability 🎉