Presence of unrecognized attributes on entities causes crashes

[Al12rs]

Outline:

If an entity has an attribute that isn't recognized, it causes the application to crash.

Details:

After rolling back from a version containing a simple attribute addition of two attributes NexusCollectionLoadoutGroup/Collection and NexusMods.Collections.NexusCollectionLoadoutGroup/Revision, the app crashes with the following stacktrace:

   00:00:10.612 [FATAL] Exception crashed the application!|System.InvalidOperationException: Attribute NexusMods.Collections.NexusCollectionLoadoutGroup/Collection not found
   at NexusMods.MnemonicDB.Abstractions.AttributeResolver.Resolve(Datom datom)
   at NexusMods.Abstractions.Loadouts.LoadoutItemWithTargetPath.ReadOnly.GetEnumerator()+MoveNext() in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutItemWithTargetPath.Generated.cs:line 287
   at NexusMods.Abstractions.Loadouts.LoadoutItemWithTargetPath.ReadOnly.Contains(IAttribute attribute) in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutItemWithTargetPath.Generated.cs:line 302
   at NexusMods.Abstractions.Loadouts.LoadoutItemWithTargetPath.ReadOnly.IsValid() in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutItemWithTargetPath.Generated.cs:line 323
   at NexusMods.Abstractions.Loadouts.LoadoutItemWithTargetPathExtensions.TryGetAsLoadoutItemWithTargetPath(ReadOnly model, ReadOnly& result) in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutItemWithTargetPath.Generated.cs:line 484
   at NexusMods.Abstractions.Loadouts.LoadoutItemWithTargetPathExtensions.OfTypeLoadoutItemWithTargetPath(IEnumerable`1 models)+MoveNext() in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutItemWithTargetPath.Generated.cs:line 499
   at System.Linq.Enumerable.IEnumerableWhereIterator`1.MoveNext()
   at System.Linq.Lookup`2.Create(IEnumerable`1 source, Func`2 keySelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.GroupByIterator`2.MoveNext()
   at System.Linq.Enumerable.IteratorSelectIterator`2.MoveNext()
   at System.Linq.Enumerable.IEnumerableWhereIterator`1.MoveNext()
   at NexusMods.Abstractions.Loadouts.LoadoutFileExtensions.OfTypeLoadoutFile(IEnumerable`1 models)+MoveNext() in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts\obj\Debug\net9.0\NexusMods.MnemonicDB.SourceGenerator\NexusMods.MnemonicDB.SourceGenerator.ModelGenerator\NexusMods_Abstractions_Loadouts_LoadoutFile.Generated.cs:line 512
   at NexusMods.Abstractions.Loadouts.Synchronizers.ALoadoutSynchronizer.BuildSyncTree[T](Entities`1 currentState, Entities`1 previousTree, IEnumerable`1 loadoutItems) in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts.Synchronizers\ALoadoutSynchronizer.cs:line 191
   at NexusMods.Abstractions.Loadouts.Synchronizers.ALoadoutSynchronizer.BuildSyncTree(Entities`1 currentState, Entities`1 previousTree, IEnumerable`1 loadoutItems) in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts.Synchronizers\ALoadoutSynchronizer.cs:line 182
   at NexusMods.Abstractions.Loadouts.Synchronizers.ALoadoutSynchronizer.LoadoutToDiskDiff(ReadOnly loadout, Entities`1 diskState) in C:\Dev\Repos\NexusMods.App\src\Abstractions\NexusMods.Abstractions.Loadouts.Synchronizers\ALoadoutSynchronizer.cs:line 710
   at NexusMods.DataModel.Synchronizer.SynchronizerService.GetApplyDiffTree(LoadoutId loadoutId) in C:\Dev\Repos\NexusMods.App\src\NexusMods.DataModel\Synchronizer\SynchronizerService.cs:line 45
   at NexusMods.DataModel.Synchronizer.SynchronizerService.<>c__DisplayClass17_0.<CreateStatusObservable>b__6() in C:\Dev\Repos\NexusMods.App\src\NexusMods.DataModel\Synchronizer\SynchronizerService.cs:line 194
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)

Even if we don't plan to support rolling back, we should still avoid outright crashing if some extra data is present on an entity.