Review template quick list usage

File and Live Templates are assigned to a quick list. IIRC, ReSharper uses this to show a limited number of templates in a popup menu, with the others available separately. Rider appears to use them only for File Templates - if the 'Add to "New" menu' checkbox is ticked, the File Template is added to the quick list and displayed in the Add -> New menu. If it's not checked, it doesn't seem to be possible to access the File Template. There is a similar checkbox for Live Templates, but the checked state doesn't seem to be remembered.

Check usage of quick lists, especially in ReSharper. Confirm that the right templates are added to the right quick lists. Looking at the code, it looks like everything could do with being renamed. What's the difference between [`UnityProjectScopeCategoryUIProvider`](https://github.com/JetBrains/resharper-unity/blob/ddb79647350a11a4d8fe72fe364d1666e897ff3f/resharper/resharper-unity/src/CSharp/Feature/Services/LiveTemplates/Scope/UnityProjectScopeCategoryUIProvider.cs#L12) and [`UnityScopeCategoryUIProvider`](https://github.com/JetBrains/resharper-unity/blob/ddb79647350a11a4d8fe72fe364d1666e897ff3f/resharper/resharper-unity/src/CSharp/Feature/Services/LiveTemplates/Scope/UnityScopeCategoryUIProvider.cs#L8)? Perhaps it would be obvious with better names. [This instance of `UnityScopeCategoryUIProvider`](https://github.com/JetBrains/resharper-unity/blob/ddb79647350a11a4d8fe72fe364d1666e897ff3f/resharper/resharper-unity/src/CSharp/Feature/Services/LiveTemplates/UnityQuickListDefaultSettings.cs#L25) shouldn't be called `filesScopeProvider`, as it defines the scopes used inside a file, by Live Templates.

Related issue: [RIDER-57619](https://youtrack.jetbrains.com/issue/RIDER-57619)