Restructure project into workspace for better codebase separation

[sandreae]

Restructure the code base in order to support GTK-free-development to occur in when it is not required. All of the backend networking logic (the p2panda bits) have been split out into their own library/crate. This allows us to use whichever IDE setup we prefer and enjoy our usual tooling during development there. Flatpak builder is still required when building/running the complete app of course.

Concretely the restructure involves:

• converting the project into a cargo workspace https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html
• introduce aardvark-app binary crate where all GTK development happens
• introduce aardvark-node lib crate where non-GTK development can happen (moved backend p2panda code there, could also move some of the automerge logic later)
• aardvark-app now depends on aardvark-node in it's Cargo.toml by path
• update meson build files in order to account for this new structure

To run build and run the app we still open the root directory in flatpak builder as is currently the case.

[adzialocha]

Looking good! I think more "idiomatic" way to name the folders would be with an underscore (aardvark_app), but that's a detail.

[sandreae]

Looking good! I think more "idiomatic" way to name the folders would be with an underscore (aardvark_app), but that's a detail.

Yeh, I thought so too, but then went with p2panda convention for consistency 😅

[adzialocha]

Yeh, I thought so too, but then went with p2panda convention for consistency 😅

Sweet, that makes sense as well!

[swick]

Good to merge?

[bertob]

I'm not qualified to review this, but no objections :)