mozjs-sys-v0.140.5-10: Publish and test debugmozjs artifacts (#544)

With this PR we also generate debugmozjs artifacts (for windows, mac and
linux; mobile platforms were skipped). Such artifacts are now loaded by
same mechanism as normal ones, so for servo developers it's just matter
of switching debugmozjs on and this will now avoid SM compilation.
Debugmozjs artifacts are not stripped, as it's users will likely need
them for debugging.

Switching between features works because `target/build/mozjs_sys-hash`,
where hash depends on features (so we get different folder for
debugmozjs \o/).

Fix #541

---------

Signed-off-by: sagudev <[email protected]>