WIP: Page Rules Implementation

[zanderwar]

This PR introduces Page Rule handling.

Primarily intended to ensure that you have Page Rules setup correctly for any SilverStripe project, you can also control your page rules. You can enable or disable page rules all without leaving the SilverStripe Administration Panel

Other module developers will be able to suggest recommended page rules via a YAML file in their _config folder

While the API provides everything you could need to create and edit page rules, it's outside the scope of this project and I implore others to create extensions, submit a PR if you want to see it.

[zanderwar]

Suggested Page Rules Markup for Other Developers

\Steadlane\CloudFlare\CloudFlare:
  suggested_page_rules:
    - name: 'Disable Security Cache'
      purpose: 'Prevents caching of the login page and other functionality'
      owner: 'My Module Name'
      mask: "*{server_name}{base_url}/security/*"
      actions:
        - id: cache_level
          value: bypass
        - id: browser_check
          value: on
        - id: security_level
          value: high

Notes:

name must be unique for it to be referenced, I felt like enough was already required without getting the developer to specify a unique slug for it.

owner must reference the package and be consistent across all suggestions

mask can be wildcarded and {server_name} and {base_url} will be parsed before any API calls