chore: refactor build pipeline

[GCdePaula]

chore(prt-tests): remove --platform from Dockerfile

[GCdePaula]

So far I've:

• introduced just and rewrote many makefiles into justfiles;
• created a single cargo workspace, and put all crates in repo under this workspace;
• reorganized directories (minor);
• built a development Dockerfile with nice caching and all dependencies (including the current branch of the Cartesi machine, which it builds), as well as building Dave.

One possible next step is removing the usage of docker in our make/just targets. Currently, we have a Dockerfile that installs all dependencies, builds the repo and run tests. Our make targets invokes docker (docker build then docker run).

I think a better workflow just invokes the intended commands, without docker, and assumes all dependencies are there (i.e. the target just test directly runs our test scripts; it assumes all the dependencies are there). Then we also provide a docker image which has these dependencies in case the developer doesn't have these dependencies installed in their system (docker run dave:dev just test).