Make `MauiCommunityToolkitMvvmEventsBinder` extensible to other elements

[albyrock87]

Problem Statement

Nowadays lots of developers are using third party libraries components which have their own Command properties which can use the MVVM command objects.

AddCommunityToolkitIntegration should provide a way to attach to those additional properties.

Solution Brainstorm

options.AddCommunityToolkitIntegration(integration => {
    integration.AddCommandSupport<MyThirdPartyElement>(
        MyThirdPartyElement.RefreshCommandProperty,
        MyThirdPartyElement.ValidateCommandProperty
    )
});

Internally this is stored as Dictionary<Type, BindableProperty[]> which we can leverage in the event binder.