Move examples out of the repo (professionalize once 1.0 is out) about catala

[AltGr]

This will include a cleanup of the Makefiles, e.g. ensuring that make build builds everything that would be installed (i.e. dune build @install, which is what make install does at the moment), and that make install actually installs it to the prefix.

[AltGr]

I am starting work on this. Here is the plan:

• Create new CatalaLang/catala-examples repository containing the contents of the examples directory
• Create new CatalaLang/french-law repository containing the contents of the french_law directory
• Adjust doc and READMEs of these repositories ;
• Adjust installation of Catala and build rules so that the examples and API uses build correctly
  There will be a catala←examples←french-law dependency chain

Now for the CI: all CI remains on the main Catala repository
(two reasons for that: these remain important tests for the compiler, and we don't want to scatter the test results or the build artifacts)

• Main catala CI: will build, test and install the compiler, then in another stage fetch the latest version of the examples / french law, build and check them, and publish their artifacts to https://catalalang.github.io/catala so that page will keep being updated as it is now
• Examples and french_law CI: the idea there is that upon update of master, the CI will do an API call to trigger a re-run of the main catala CI (that will fetch the newer version of the repo) ; this will ensure that the artifacts page is always up-to-date with both Catala and the examples/french-law repos.
• A specific CI for PRs on examples and french-law (that could use the published builds of the catala compiler ?) will probably be useful soon enough.

[AltGr]

Also: for now I intend to disable the bug-trackers on the two new repos, so that we keep all issues in the same place (the tracker of the main Catala repo)

[denismerigoux]

You plan looks good Louis ! And OK for disabling the bug trackers in the other examples. Do you think that you could extend your CI streak to cover update of the Catala websites catala-website and catala-dfsr too?