Update the settings UI

[elistone]

Is your feature request related to a problem? Please describe.
The current settings UI consists of two sections, one giving an overview of what is enabled and the other an editable json textarea.

The overview is not that detailed, and the way to add/edit/delete notifications is not very intuitive.

Describe the solution you'd like
It would be great to overhaul the settings page so that the overview page is more consistent.
The way to add/edit/delete could be attached to this overview section with action buttons, that use things like text boxes and dropdowns.
The json editor can still stay the same as it is useful import/export.

Tasks

• Improve the look of overview page
• Create in options to edit / delete notices
• Create in edit section / page
• Create an add section / page
• Confirm/warn before deleting
• Enforce the field options based upon type