Provisioner settings integration

[CalvinKrist]

Is your feature request related to a problem? Please describe.
As a provisioner developer, I want to be able to specify variables in my provisioner that are convenient to edit and can be edited in ways that I specify.

Describe your solution to the problem
The developer could define an HTML file using a template system such as Jinja2. That template could then be used as the provisioner settings. Specific classes and id's would allow provisioner developers to ignore most of the JavaScript going on behind the scenes.

The template is then placed into the settings modal and the user can edit it.

Describe altenratives
A separate configuration file, probably JSON, says how the variables can be edited. For example, variables could be text input following some regex, a slider menu, a toggle switch, etc.

From the configuration file, an HTML file is created and used as the provisioner settings menu. The rules described in the configuration file are then enforced, and the resulting variables are used in the provisioner download.

• Determine what predefined classes would simplify the template development work in a good way
• Implement said classes
• Create a tutorial on creating a template
• Document the classes created, and the basics of the template system
• Implement the variable retrieval through the Python side
• Define the variables in the corresponding provisioner scripts