Adds fidesops worker command to start the Celery worker [#663]

[seanpreston]

Purpose

This PR adds some general Dockerfile hygiene and the fidesops worker which can serve as the entrypoint into the celery worker nodes.

Changes

• Renames fidesops to webserver
• Renames celery to worker
• Renames redis to cache
• Adds fidesops worker click CLI command to bring up a worker

Checklist

• Update CHANGELOG.md file
  • Merge in main so the most recent CHANGELOG.md file is being appended to
  • Add description within the Unreleased section in an appropriate category. Add a new category from the list at the top of the file if the needed one isn't already there.
  • Add a link to this PR at the end of the description with the PR number as the text. example: #1
• Applicable documentation updated (guides, quickstart, postman collections, tutorial, fidesdemo, database diagram.
• If docs updated (select one):
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • documentation issue created (tag docs-team to complete issue separately)
• Good unit test/integration test coverage
• This PR contains a DB migration. If checked, the reviewer should confirm with the author that the down_revision correctly references the previous migration before merging
• The Run Unsafe PR Checks label has been applied, and checks have passed, if this PR touches any external services

Ticket

Fixes #633

[sanders41]

This change in the Makefile will fix the docker-build error. Everything else looks good.

- docker-build:
-	docker build --tag $(IMAGE) .
+ docker-build:
+	docker build --tag $(IMAGE) -f Dockerfile.app .