restore defaults button/ ability to toggle between default and changed color settings

[interim17]

Use Case

Advances #511

Once color settings have been changed (by user selections or by retrieving stored settings from the browser) the user should have the ability to preview and then apply the default color settings.

Acceptance Criteria

Button in side panel should exist and be deactivated while the defaults are applied.
Once current settings do not match the default the button should become active.
On hover it should retain changes in state, but temporarily apply the default as a preview.
On click the default should be applied permanently and the changed colors should be removed from state and browser storage.