Add js_of_ocaml debug flags

[Halbaroth]

Currently, we compile the js worker without debug flags in our makefile.
I got an annoying bug while adapting the worker for Dolmen and without the
dev flags of dune, it was impossible to debug. I think it is better to
build it with the profile dev by default.

I also add more debugs flags at the toplevel of our worktree.

[Halbaroth]

Uhm, it seems that the node version does not compile correctly with the dev profile. This issue is already present on next:

dune build src/bin/js/main_text_js.bc.js --profile release 
node _build/default/src/bin/js/main_text_js.bc.js tests/everything/f1.ae 
File "tests/everything/f1.ae", line 159, characters 1-166: Valid (0.3200) (240 steps) (goal WP_create)

but

dune build src/bin/js/main_text_js.bc.js --profile dev 
node _build/default/src/bin/js/main_text_js.bc.js tests/everything/f1.ae 
Fatal error: exception Failure("caml_register_global: cannot locate Dynlink_compilerlibs.Binutils")