Modpack compatibility prompt, GameComparator clean-up

[HebaruSan]

Motivations

If you try to install a modpack from a .ckan file, you may have (potentially much) narrower compatibility settings than the modpack creator, which can prevent some dependencies from being found and make the installation fail.

In #3675, we added a prompt to notify users when this might happen:

However, this doesn't really present a clear, reliable path forward for the user; if they click Cancel, the installation aborts, and if they click Install, the installation will continue but might fail. What we really need is a way to guide users to extend their compatibility settings so the install can both continue and succeed.

Changes

Now before that prompt appears, a better one shows up:

If the user clicks "Add compatible versions", then we auto-update their compatibility settings to be a superset of the modpack's compatibility (which is based on the modpack .ckan file's ksp_version_min and ksp_version_max settings, which are based on the compatibility settings of the modpack creator), which should guarantee a successful install. If they instead click "Keep current compatibility", then we leave their settings alone, and they will still get warned about any specific incompatibilities.

Other changes

While developing this, I noticed some problems with the IGameComparator family of classes:

• GrasGameComparator treats version 1.0.4 as implicitly compatible with 1.0.3, which is KSP1-specific logic that should not be applied to other games. It's very unlikely that anyone is relying on this behavior, and if they are, the compatible versions setting is a better approach anyway.
• YoyoGameComparator isn't used for anything

These classes and the files containing them are now deleted, and we now only use StrictGameComparator to check module compatibility.