Add support for NSS trust stores under linux

[plexus]

Firefox profiles are under ~/.mozilla/firefox

Chrome/Chromium uses ~/.pki/nssdb , or profile-specific ~/snap/chromium//.pki/nssdb.

This will install the cert in every profile it finds. It also saves the output of certutil, which gets printed out in case something goes wrong.

I hope you don't mind the extra bits (the :main alias in deps.edn and the storing of certutil output), I can remove those if you prefer.