Exclude dependencies in the changeset from supported by list

[HebaruSan]

Problem

If you install BoringCrewServices, KSPCommunityPartModules will be listed as a dependency in the changeset, but also as optional in the "Supported By" list. It doesn't make sense for it to be in both places.

Reported by @SofieBrink and @AlexSkylark in Discord.

Causes

• BoringCrewServices depends on KSPCommunityPartModules, which adds the latter to the changeset as a dependency
• KSPCommunityPartModules supports BoringCrewServices, which adds the former to the "Supported By" list
• The relationship resolver currently excludes only the mods that you directly selected from the "Supported By" list, not their dependencies (probably because this relationship structure doesn't actually make sense)

Changes

Now ModuleInstaller.FindRecommendations passes recommenders to RelationshipResolver.Supporters instead of toInstall. This will exclude dependencies of the selected mods from the "Supported By" list.