Motivation for this change

This backports @taku0's firefox 62 update PR #46157 to 18.03.

The many difference to the original branch is that. I did not end up upgrading to a compatible sqlite version (0.23.0 IIRC) sine that introduced a bunch of failures (e.g. sqlalchemy started failing etc..). Instead the bundled sqlite version is being used. I did not want to introduce yet another mass-rebuild and a bunch of package bumps just because firefox gets bumped. 18.09 is already on it's way and this will hopefully be (one of) the last firefox upgrade we have on 18.03 :-)

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.