External CloudFlare resolver (#245)

Adding support for an external CloudFlare bypasser service and
introducing a new Docker image build with a dedicated target.

Key Changes
- Added `cloudflare_bypasser_external.py` for external bypasser
integration.
- Updated Docker Compose files to support the new service.
- Introduced a new Docker target for building a separate image for the
external bypasser.
- Refactored relevant modules to utilize the external bypasser when
configured.
- Documentation and configuration updates to reflect new options and
Docker targets.

Impact
- Users can now choose between internal and external CloudFlare
bypassing.
- New Docker image and target streamline deployment of the external
bypasser.
- Improved modularity and maintainability.
- No breaking changes for existing workflows.

Testing
- Manual and E2E tests performed for both bypasser modes.
- Docker Compose setups and new image build verified for development and
production.

Notes
Please review the new configuration options and Docker targets. Update
your environment and deployment scripts as needed. Feedback and
suggestions are welcome!

.github/workflows/build-and-publish-docker-image.yml

@@ -26,6 +26,9 @@ jobs:
           - suffix: "-tor"
             target: cwa-bd-tor
             image_name_suffix: "-tor"
+          - suffix: "-extbp"
+            target: cwa-bd-extbp
+            image_name_suffix: "-extbp"
     steps:
       - name: Get current date
         id: date