PoC Spectre.Console

[gruenwaldlk]

Discussed in #175

^{Originally posted by gruenwaldlk April 29, 2021}
@SvenMarcus suggested that we switch from the default console to Spectre.Console which does look like a promising balance between keeping the tool as a CLI application that is also intended for the use with CIs and providing the possibility of a more user friendly frontend.

This discussion is mostly aimed at figuring out which parts need to be changed or updated to achieve that goal.

[SvenMarcus]

I think the current reporting structure is a good start, so that using the basic features of Spectre without changing our application core shouldn't be a problem.
If we want to use progress bars for things like copying or uploading then we need to extend the live reporting capabilities a bit.

[gruenwaldlk]

I had a basic look at it today, bit more work than I thought, because we do have to swap stuff out into commands and Spectre specific constructs if we want to use Spectre.Console.Cli instead of the current library, so the application host and a few general organisational things will have to change. I'll probably also use the chance to fixup the current DI setup, because that's mostly half-assed on my part.