Added support for iAsyncDisposable

[klemmchr]

Closes #43

[klemmchr]

@BrentCarter could you have a look whether this changes would suffice for you? Thanks a lot!

Don't worry about the amount of changes. I needed to do an upgrade to .NET 5 in order to achieve this. The relevant Part is here

This will also result in a breaking change and therefore in an increase of the major version.

[BrentCarter]

Thanks for getting into this. I just took a look and see that IAsyncDisposable support was added to MvvmComponentBase, which is great, but I guess I was sort of expecting it would be on ViewModelBase as well. Is there a reason to have it on the component but not the VM given the VM does implement the non-async version? I'm still evaluating and learning different patterns for Blazor so I don't have an active project using this library yet, so I can't point a specific use I need it for... but it seems like that might be useful.

[klemmchr]

You're right, I missed that. Actually the IDisposable implementation in ViewModelBase serves no real purpose from looking at it. It seems like it was used at some point but I left the empty implementation. Gonna remove it then.