Cleanup ShellDescripterFeaturesManager

[MikeAlhayek]

@jtkech here is a PR to clean up the ShellDescriptorFeaturesManager after PR #12281 was merged

[jtkech]

You can remove this .ToHashSet().

Hmm but replace it with a .ToArray() so that it is not lazy evaluated twice below.

then I will merge

[MikeAlhayek]

@jtkech I made the change. Any reason why ToArray() instead of ToHashSet()? Either way I made the changes. Its ready to be merged. Maybe ToList() https://stackoverflow.com/questions/1105990/is-it-better-to-call-tolist-or-toarray-in-linq-queries

[jtkech]

Okay thanks

Both prevent re-evaluation, ToHashSet is useful when we then use Add/Remove and it will compare to existing items in an optimized way, works with strings and classes that are IEquatable otherwise the comparizon is by ref (object pointers are compared) which works too if a given featureInfo is always related to the same object instance, which I think it is the case here as they are always returned from the extensionManager that doesn' clone items collection but ...