[snarkyjs-bindings] check if overrides.js and sed cmd are still necessary

[dannywillems]

From Slack conv:

the stubs look different in jsoo master
for the function defines in overrides.js: https://github.com/ocsigen/js_of_ocaml/blob/master/runtime/sys.js#L85 and https://github.com/ocsigen/js_of_ocaml/blob/master/runtime/fail.js#L33
Running git diff 4.0.0 runtime/sys.js and git diff 4.0.0 runtime/fail.js on jsoo master.
'll give a try in the bumpup
I don't know if the attach_backtrace does smth interesting

At the moment, overrides.js overrides fail functions, caml_fatal_uncaught_exception and caml_raise_with_string to include the stack trace. However, looking quickly at jsoo master, it seems the backtrace is added?
It would simplify the code and the integration in dune.

Maybe also we could get rid of the sed cmd when bumping jsoo