Recommendations usability improvements

[HebaruSan]

Motivation

• If you install OuterPlanetsMod and UnKerballedStart, two of the latter's recommendations conflict with the former, so you have to uncheck them to continue:
  
• If there's a particular mod that you've decided you never ever want to install, you can add it to a held or hidden label, but the recommendations screen will still check it by default if a mod you're installing recommends it
• The recommendations screen has a checkbox that can toggle all the checkboxes on and off, but it's very common for users not to notice it or understand how it works, so they uncheck boxes one by one
• By default, recommendations are checked by default and suggestions are unchecked by default. Some users have requested an option to make recommendations unchecked by default.

Changes

• Now recommendations that conflict with any installed or installing mods are unchecked by default
• Now recommendations with held or hidden labels are unchecked by default
  (In the below screenshot, Bureaucracy is in the Held label)
• The checkbox is replaced by toolbar buttons:
  • Uncheck All - unchecks all the boxes
  • Check All - checks all the boxes
  • Check Recommendations - Checks all the recommendation boxes without changing the other sections
• The Mod description column is now auto sized to fit the width of the listview without a horizontal scrollbar

The dropdown button next to Uncheck All shows a menu with an Always uncheck all checkbox:

If you check this, then GUIConfiguration.SuppressRecommendations is set to true, and the next time you come to the recommendations screen, nothing will be checked by default. You can uncheck the box to go back the normal defaulting behavior.

The "Check" toolbar buttons become enabled and disabled based on whether any of their affected mods are unchecked, but the "Uncheck" button is always enabled because if we disable it we lose access to its dropdown menu.

Fixes #4011.
Fixes #4015.
Fixes #4016.