feat(*): allow for filtering the playbook by role

Allow for appending ansible-playbook arguments to the dotfiles script,
and automatically applying tags to the included roles.

For example:

`./bin/dotfiles --tags=neovim`

bin/dotfiles

@@ -23,4 +23,4 @@ run_playbook() {
 
 clone_or_update_dotfiles
 install_dependencies
-run_playbook
+run_playbook "${@}"