[FEAT]: CI - Pass full backstopjs package name/version to Docker

[dgrebb]

Summary

Let's allow the backstopjs package installation to be passable in args during Docker build.

Why?

This will allow GitHub actions to pass the current backstopjs branch to Docker, so build, publish, and tests are run with the latest changes this branch has introduced.

How?

• rename the Dockerfile ARG "BACKSTOPJS_VERSION" → "BACKSTOP_INSTALL_SOURCE"
• adjust the ENV BACKSTOPJS_VERSION=$BACKSTOPJS_VERSION → BACKSTOP_INSTALL_SOURCE=$BACKSTOP_INSTALL_SOURCE
• adjust npm scripts as needed
• create GitHub Actions var BACKSTOP_INSTALL_SOURCE to concatenate installation source path
• update GitHub Actions to pass the BACKSTOP_INSTALL_SOURCE to Docker builds
• check if any $TAGs need to be adjusted

[dgrebb]

@garris FYA — another improvement for your consideration. This would include any changes to backstopjs within Docker as part of the overall regression suite.

Currently one must commit a change to Dockerfile to include a GitHub branch path to test changes within npm backstop itself:

diff --git a/docker/Dockerfile b/docker/Dockerfile
index 18c3691..9460944 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -26,7 +26,7 @@ RUN apt-get -qq update >/dev/null && apt-get install -qq \
 ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true
 # playwright shared browser path (does install a 2nd chromium - can't be skipped)
 ENV PLAYWRIGHT_BROWSERS_PATH=/opt/pw-browsers
-RUN mkdir ${PLAYWRIGHT_BROWSERS_PATH} && npm install -g --unsafe-perm=true --allow-root backstopjs@${BACKSTOPJS_VERSION} && npx --yes --verbose --foreground-scripts playwright install --with-deps
+RUN mkdir ${PLAYWRIGHT_BROWSERS_PATH} && npm install -g --unsafe-perm=true --allow-root dgrebb/backstopjs#downstream/feature-1525-headless-mode-deprecation && npx --yes --verbose --foreground-scripts playwright install --with-deps

Super hard to explain. This feature is a good candidate for first-hand review when it's ready.