Add Mac Catalyst TFM to all iOS plugins
## 🚀 Feature Requests

Add Mac Catalyst support to all iOS plugins.

### Contextualize the feature
MvvmCross itself already targets `net6.0-maccatalyst` so it's not a big deal to add that to the plugins.
MvvmCross:
https://github.com/MvvmCross/MvvmCross/blob/9.0.9/MvvmCross/MvvmCross.csproj#L3
Visibility plugin:
https://github.com/MvvmCross/MvvmCross/blob/9.0.9/MvvmCross.Plugins/Visibility/MvvmCross.Plugin.Visibility.csproj#L3

### Describe the feature
It's nice to be able to debug your Mac Catalyst app (iOS app for MacOS) right on a Mac with M1 but currently lack of plugins does not let to do that properly.

### Platforms affected (mark all that apply)
- [x] :iphone: iOS
- [ ] :robot: Android
- [ ] :checkered_flag: WPF
- [ ] :earth_americas: UWP
- [x] :apple: MacOS
- [ ] :tv: tvOS
- [ ] :monkey: Xamarin.Forms
- [ ] :🌍: Blazor
