refactor justfiles / test commands

[syphar]

I tried to revisit all the just commands, coming from my current usage under linux, also thinking about my past usage as mac user. #3474, #3472, #3475, and #3473 were actually intermediate steps I pulled out into separate PRs.

My goal is actually that I'm using all these commands myself, instead of my shell history.

Main points:

• by default on a dev machine, the binaries should be directly used, locally via cargo run -p, on all operating systems. You can switch to using the containers if you want.
• the builder should do cargo run only on linux, otherwise use the builder docker container, since our builder doesn't work otherwise.
• gui-tests should run without docker on dev machines, only in CI we want all in docker to know it works. In any case, I dropped the Dockerfile.gui-tests and we'll always run the tests on the runner. With this, locally iterating on the gui-tests works super smooth.
• I want to easily run the CI checks locally via a recipe, when fixing stuff.

Generally I see this just as "the first idea", and will iterate over the next weeks when I use them.

Other small changes:

• all these super small cli-xx- recipes are dropped, people can just use just cli SOME ARGS. Downside: no recipe autocomplete. Not sure yet what I like more.

[syphar]

r? @GuillaumeGomez