Fix Audit Recommendations option

[HebaruSan]

Problem

If you have any DLCs installed in a KSP1 instance, the Audit Recommendations option doesn't work.

Cause

As of #3892, ModuleInstaller.FindRecommendations uses RelationshipResolver to get the recommendations and suggestions for the full dependency tree of a given group of mods. (Previously it had a lot of its own duplicative logic that has been refactored to use the shared logic in RelationshipResolver.)

Audit Recommendations passes the list of installed modules, which includes DLCs, and RelationshipResolver throws ModuleIsDLCKraken when it finds a DLC in its input.

Changes

Now ModuleInstaller.FindRecommendations filters DLCs out of the sequence of modules it passes to RelationshipResolver, so the exception is no longer thrown and Audit Recommendations works again.

We could have had GUI.Main.AuditRecommendations do this instead, but it seems more appropriate to enforce the constraint at the point where RelationshipResolver enters the picture.

Fixes #3987.