Changes to the app.html layout, mainly:
- A new panel is created to hold action buttons. Closes#1698.
- Launch button is now shown in the panel alongside "Client Apps".
- Run Diagnostics button is moved into this panel as well. Closes#1690.
- Disable 'Launch web client' button when app is disabled. Closes#1718.
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>