Adds a setting UI to list all configured playgrounds
in a realm. The filter functionality can be used to
search playgrounds by its name or language.
Default sort is provided on the 'pygments_language'
field.
Front tests added to maintain server_event_dispatch
coverage. The `settings_playgrounds.js` file is added
to coverage exclusion list since it is majorly UI
based and will be tested using puppeteer tests (in
following commits).
Sumanth V Rao