Port to `Terminal.Gui` V2

[tig]

The Terminal.Gui team is rapidly converging on the launch of V2.

We've made it a V2 Beta release criteria that OCGV is ported. It's a V2 Release critera that OCGV based on V2 is releasable by MS.

This Issue is to track this on the OCGV side.

It is my ambition to make OCGV "v2" have feature parity with the current version plus address most of the currently open issues for new functionality.

I'll be opening a draft PR for this soon...

See https://github.com/orgs/gui-cs/projects/5 for more