add CI / ocamlformat / split packages

add CI : a minimal CI to build the package with all the system dependencies

ocamlformat : add dune build @fmt and reformat the code

src: move all the ocaml code in src

packages: use dune-project to generate opam files and split the package in 3 subpackages ( teztale, teztale-server, teztale-archiver )

TODO:

• create a teztale-archiver without depopts