Migrate to Avalonia for cross-platform support

[vector-man]

In order to get IPS Peek running on other platforms, it will need to be migrated to another UI framework (dropping Windows Forms.) I have decided to settle on Avalonia as the framework.

Migration will occur sometime after the rewrite with ReactiveUI. But it may not be immediate, depending on user demand.

Update (5/29/2023): Avalonia will eventually allow for Mac, Android and web support. Right now, the Avalonia GUI is very work-in-progress.

Steps to be taken:

1. Finish Avalonia GUI (retaining the WinForms Be.HexBox control in a NativrControlHost, still tying it to Windows-only).
2. Move all WinForms backend functionality over to Avalonia version.
3. If/when a suitable Hex control for Avalonia is available, swap HexBox's out, making IPS Peek cross platform.

[vector-man]

I've created an experimental branch for Avalonia, locally. It contains a very early, yet somewhere functional version.

I will not be able to do much more, without a suitable Hex editor for Avalonia. For now, I'll concentrate on the WinForms releases.

[vector-man]

Pushed an Avalonia branch, with what's available so far: https://github.com/vector-man/IPS-Peek/tree/avalonia

[vector-man]

I decided to help get WPFHexEditor onto Avalonia. It's going to take quite a long time to rewrite (because of so many projects), so this is looking like months away.