chore: ControlLibrary Sample - Update to net6

[aesteves900]

No description provided.

[nickrandolph]

@aesteves900 a couple of points:

• This sample is supposed to demonstrate referencing a templated control from a referenced control library (see #MyTemplatedControl that's contained within the XamlControlLibrary project. Don't just include MyTemplatedControl in the shared project
• The sample is missing some of the uno targets (eg wpf, gtk, linux). Make sure the sample includes all uno targets
• It looks like the Wasm and Android targets (and probably others) aren't rendering the custom control. Can you please make sure you test the samples on all platforms. This issue is probably related to the first point - if you restructure the code as per the original sample, this should fix this issue.

[aesteves900]

Hello @nickrandolph

• Okay I will fix that
• Could we create an issue for that? According to Jerome we need to update each sample as-is.
• I fixing the issue, because the control rendering on Windows properly.

[nickrandolph]

Closing this as this sample has already been updated now