[MVUX][ListState] Add support for UpdateSelectedItem or non-`KeyEquatable<T>` types containd in a ListState!

[DevTKSS]

What would you like to be added:

1. Provide possibility to Update the Current Selected Item(s) with a UpdateSelectedItem(s)Async(
   1. Also for simple types that do NOT implement IKeyEquatable<T>!!!
   2. Regular record types of course too
2. Best case would be, if this IKeyEquatable<T> Limitation would not at all be existing for UpdateItemAsync!

Why is this needed:

A Viewer of my MVUX tutorials asked me to do a simple Tutorial for how we can:

1. Select a Item of a ListState<string>
2. Update this Item with the new Value

We tryed for about 2-3 hours because this is not possible to be used with a non IKeyEquatable<T> implementing type, like string!

From Consumer Side, it's absolute non-sense to always have to create a dedicated Record Type just to use Mvux or else we seem to be confronted with such errors!

Another reason why we would need this: What if the IKeyEquatable would match more then the ones selected? We would unintentionally update those too.

For which Platform:

• All Platforms
• Build tasks

Anything else we need to know?

Related Issues:

• [Docs] PropertySelector and KeyEqualityComparer not listed in the TOC #2831
• Docs should be updated [Docs][Mvux][ListState] UpdateItemAsync is not possible like showed in the docs if the item is a simple string #2881 - docs(MVUX): Introduce reader in how to use UpdateAllAsync for simple types like string #2927
• We are required to use UpdateAllAsync [MVUX] UpdateAllAsync + Command Binding still causes null value Selection #3002 while ONLY want to update that one currently even selected Item
• Usage in Business Applications
  • [Mvux][ListState] Can we get a DictionaryState beside a ListState using a ReactiveDictionary? #2709
  • This would eventually allow implementing non-IKeyEquatable<T> ListState's to get the regular UpdateItemAsync too: [MVUX][ListState/ListFeed] Add Method/Argument/Identifing Parameter for CRUD Elements per index inside of ListState/ListFeed #2922