Add schema validation to anyconfig data

[Grokzen]

Environment

• Phabfive version: latest
• Python version: 3.x

Proposed Functionality

Add json schema validation to the internal data/config that is using anyconfig to build the config file based on files on disk.

https://python-anyconfig.readthedocs.io/en/latest/usage.html#validation-with-and-or-generate-json-schema

An example/WIP schema.yaml:

type: object
properties:
  PHABFIVE_DEBUG: {type: boolean}
  PHAB_TOKEN: {type: string}
  PHAB_URL: {type: string}

Use Case

None

Other?

None