Run web API test suite in GitHub Actions (#1009)

- Fixed ignore patterns in .dockerignore
- Added healthchecks to backend and web containers
- Reduced Docker image sizes
- Removed RaSCSI references in various areas (e.g. rascsi -> backend)
- Added compilation-only step to easyinstall.sh
- Moved apt package lists to variables
- Revert to triggering GitHub Actions runs on push
- Updated web/frontend_checks workflow to run black and flake8 against all Python sources
- Capture log files from backend/web containers
- Fix None to float conversion bug when user agent is absent or unrecognised

python/web/mock/bin/git

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+exit 0