[Collection view] Handle a reselect scenario

[kubaflo]

A common scenario is that users will select something and then navigate away. Once they navigate back the element is still selected which will result in users being unable to reselect the given item.

https://github.com/dotnet/maui/pull/21490#discussion_r1623301225

The original issue also points to our samples, because our samples don't allow reselection. https://github.com/dotnet/maui/issues/20273

Fixes https://github.com/dotnet/docs-maui/issues/2362

[jfversluis]

Would it also fix this one: https://github.com/dotnet/maui-samples/issues/484?

[kubaflo]

Would it also fix this one: #484?

I think it won't