Move EE-specific stylesheets to `ee/app/assets/stylesheets` directory
› git diff ce/master..origin/master --name-status ./app/assets/stylesheets | grep -e '^A' | cut -f2
app/assets/stylesheets/framework/sortable.scss
app/assets/stylesheets/pages/billings.scss
app/assets/stylesheets/pages/ee_start_trial.scss
app/assets/stylesheets/pages/geo_nodes.scss
app/assets/stylesheets/pages/issues/related_issues.scss
app/assets/stylesheets/pages/licenses.scss
app/assets/stylesheets/pages/promotions.scss