Classes to encapsulate Grok & ImageMagick system calls

[mwarin]

This PR mainly moves some code out of inline system() calls and into more "proper" perl classes. There isn't much (any?) functional change... we're still doing the same things, just using different code to do it.

• Tidied a bit
• Broke out system calls from HTFeed::Stage::ImageRemediate into new classes HTFeed::Image::Grok and HTFeed::Image::Magick (plus some shared functionality in HTFeed::Image::Shared)
• Added tests for new classes
• Added new dev tool / test util: fail_fast.sh
• Added a directory for reference images, thinking this will make it easier to test image operations

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Review request

I'd like eyeballs on the 2 new classes Grok & Magick & new test image.t.
Check that you can build & test green:

git clone https://github.com/hathitrust/feed.git
cd feed
docker compose build
docker compose run --rm test bash t/fail_fast.sh t/*.t

The fail_fast.sh output should, if all was OK, end with:

volume.t : t/volume.t

[liseli]

Executing this command docker compose run --rm test bash t/fail_fast.sh t/*.t

I see the error below. Although it seems you did not update the t/classtests.t script, this test could be impacted with four changes.

lisepul@2379591497 feed % docker compose run --rm test bash t/fail_fast.sh t/*.t [+] Creating 4/0 ✔ Container feed-rabbitmq-1 Running 0.0s ✔ Container feed-pushgateway-1 Running 0.0s ✔ Container feed-minio-1 Running 0.0s ✔ Container feed-mariadb-1 Running 0.0s 001_load.t : t/001_load.t 002_load_all.t : t/002_load_all.t backup_expiration.t : t/backup_expiration.t gpg: error opening lockfile '/usr/local/feed/.gnupg/pubring.kbx.lock': No such file or directory gpg: lockfile disappeared bunnies.t : t/bunnies.t classtests.t : t/classtests.t HTFeed::Namespace::Test is not Test::Class or integer at t/classtests.t line 26. Error at t/classtests.t see /tmp/perltest_results/classtests.t

[mwarin]

@liseli I don't understand why that error would happen, and you're right that's not part of the changed files.
When confronted by mysterious errors I usually blame the cache, nuke the cache, and run the tests again.
You could also run the tests in the same way as .github/workflows/tests.yml :

docker compose run test-and-cover

[liseli]

Due to some unexpected issues, I could not run the tests locally. Martin and I set together to try to fix but it seems so complex. This PR does not introduce new features, it only gets a better organization of the functionalities. The change makes sense to me and I will approve it.