fix: Erlang bin path to user PATH, don't reinst

 - 100MB download was running again, even if installed already
 - need to ensure the bin dir is in PATH for access to erl
 - Handle PATH manip in install and uninstall
chore: bump Erlang to 16.0.1 to fix install issues
feat: Elixir 0.10.0 package first release

 - ensure Erlang and toolsroot are installed
 - add bin directory to PATH
 - uninstall removes Elixir from tools directory and removes PATH mods