Add an acceptance test for Celerity maps

Summary: Fixes T5374. Add an acceptance test to the `PhabricatorInfrastructureTestCase` class which fails if a Celerity map is not up-to-date. In order to achieve this, a lot of code used to generate Celerity maps was transferred from `CelerityManagementMapWorkflow` to `CelerityResourceMap` and `CelerityResourceMapGenerator`.

Test Plan: Ran `arc unit` and noticed that all tests passed. Modified a JavaScript file and ran `arc unit` again (without running `./bin/celerity map`)... this time the test failed, as expected.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T5374

Differential Revision: https://secure.phabricator.com/D9817