Reimpl ocamlary test using Mdx

[Julow]

There is some problems with this approach:

• It is slow (more than 30 seconds to run on my laptop)
• The output is huge (38k lines)
• It has some ad-hoc paths to cm{t,i,ti} files that are specific to dune
• The plugin I use to fold markdown sections is scanning 1/3 of the file at every change

The advantage is that the toplevel can print any values. I use some custom printers to shorten the representation of some values (Location_.with_location and Root.t). I didn't manage to have short-paths working.

Do you think we can skip testing cmt and cmi files ?

[Julow]

Too slow and output too big. Let's close this for now. We could reuse the top of ocamlary.md, though. There is code to make the output nicer, what do you think?