Satisfy dependencies with installed incompatible modules

[HebaruSan]

Problem

If you force-install an incompatible module (with no compatible versions), then try to install a mod with a recommendation that depends on it, you get this in the recommendations screen:

CKAN.DependencyNotSatisfiedKraken: Exception of type 'CKAN.DependencyNotSatisfiedKraken' was thrown.
  at CKAN.RelationshipResolver.ResolveStanza (System.Collections.Generic.IEnumerable`1[T] stanza, CKAN.SelectionReason reason, CKAN.RelationshipResolverOptions options, System.Boolean soft_resolve, System.Collections.Generic.IEnumerable`1[T] old_stanza) [0x0038f] in /home/DasSkelett/git/CKAN/Core/Relationships/RelationshipResolver.cs:434 
  at CKAN.RelationshipResolver.Resolve (CKAN.CkanModule module, CKAN.RelationshipResolverOptions options, System.Collections.Generic.IEnumerable`1[T] old_stanza) [0x00038] in /home/DasSkelett/git/CKAN/Core/Relationships/RelationshipResolver.cs:318 
  at CKAN.RelationshipResolver.AddModulesToInstall (System.Collections.Generic.IEnumerable`1[T] modules) [0x00189] in /home/DasSkelett/git/CKAN/Core/Relationships/RelationshipResolver.cs:260 
  at CKAN.RelationshipResolver..ctor (System.Collections.Generic.IEnumerable`1[T] modulesToInstall, System.Collections.Generic.IEnumerable`1[T] modulesToRemove, CKAN.RelationshipResolverOptions options, CKAN.IRegistryQuerier registry, CKAN.Versioning.KspVersionCriteria kspversion) [0x00028] in /home/DasSkelett/git/CKAN/Core/Relationships/RelationshipResolver.cs:183 
  at CKAN.ChooseRecommendedMods.FindConflicts () [0x00001] in /home/DasSkelett/git/CKAN/GUI/Controls/ChooseRecommendedMods.cs:116 
  at CKAN.ChooseRecommendedMods.MarkConflicts () [0x00001] in /home/DasSkelett/git/CKAN/GUI/Controls/ChooseRecommendedMods.cs:87 
  at CKAN.ChooseRecommendedMods.RecommendedModsListView_ItemChecked (System.Object sender, System.Windows.Forms.ItemCheckedEventArgs e) [0x00045] in /home/DasSkelett/git/CKAN/GUI/Controls/ChooseRecommendedMods.cs:81 
  at System.Windows.Forms.ListView.OnItemChecked (System.Windows.Forms.ItemCheckedEventArgs e) [0x00019] in <f8d3988c81fd41129e6b0d880060d203>:0 
  at System.Windows.Forms.ListViewItem.set_Checked (System.Boolean value) [0x0006c] in <f8d3988c81fd41129e6b0d880060d203>:0 

If you try to install a mod that depends on the depending mod, without the recommendations step:

Somehow if you simply install a mod that depends on the manually installed mod, that works fine. No idea why, RelationshipResolver is magic. 🌠

Cause

RelationshipResolver.MightBeInstallable, which is used as the first-pass basic installability checker, only looks at compatible available modules to satisfy dependencies. It doesn't check installed modules at all.

Changes

Now dependencies that are satisfied by an installed module will be treated as satisfied.

The DependencyNotSatisfiedKraken also has some more informative default reason messages.

Fixes #3134.

[DasSkelett]

Urgh, the most complex issues always have the simplest fixes.
Thanks for digging through this!