Create flag to turn off "provision content" and "reset settings" from theme settings

Problem/Motivation

Currently, you can provision content from theme settings in a sub-theme or civictheme. This is great when you are provisioning / setting up a site.

Not great when you are changing theme settings on a production site.

I propose there is a "Development mode" theme setting or flag that can get turned off once a site is provisioned.

Proposed resolution

Add flag or theme setting to disable the 'dangerous' theme settings. (Dangerous being create content / modify content on the site).