One policy definition to rule them all!

Summary

As a developer, I want there to be a single authoritative definition of the JSON policy so that I stay DRY.

cloudigrade and frontigrade currently store the JSON policy definition in separate places, but it sure would be nice if there was one definitive source that they both used. Now that cloudigrade has a "sysconfig" endpoint that provides general global information to the frontend UI, perhaps we should extend its result to include the full JSON policy definition, and then frontigrade should pull that and inject it onto the page.

Acceptance Criteria

• Verify JSON policy is pulled from the API and not duplicated in frontigrade

Assumptions and Questions

• Do we need new automated tests for this? Maybe it would be "enough" to see existing tests around "Add Account" continue passing and not fail?
• Be sure to update the API docs with the changes to sysconfig.
• The updated sysconfig response should be able to return multiple policy definitions because in the near future we will have two different policy definitions to use in different account inspection use cases.