chore: add slot to allow additional course app plugin (#941)

* chore: add @openedx/frontend-plugin-framework

chore: move plugin page setting button to a props

chore: split out app setting modal for reusability

chore: add implementation of WTC plugin

chore: update app setting form

chore: implement the plugin form with mock

chore: follow the UI design

chore: remove translation plugin and move it into frontend-plugin instead

* chore: add eslint ignore for env.config.jsx

* chore: update package-lock.json

.gitignore

@@ -26,3 +26,6 @@ temp/babel-plugin-react-intl
 
 # Messages .json files fetched by atlas
 src/i18n/messages/
+
+# environment js config
+env.config.jsx