Bump shakapacker to 9.5

[aaccensi]

Description

Bumped shakapacker in 3 stages:

Stage 1: 6.0 to 7.2.3 (v7 upgrade guide)

File	Change
config/webpacker.yml	Renamed to config/shakapacker.yml
config/shakapacker.yml	Updated cache_path and comment
config/webpack/webpack.config.js	Changed webpackConfig to generateWebpackConfig()
Gemfile	Updated shakapacker 6.0.0 to 7.2.3
package.json	Updated shakapacker 6.0.0 to 7.2.3
Gemfile.lock	Updated with bundle update shackapacker ==conservative
yarn.lock	Updated with yarn install
docker-compose.yml	Env var names updated:WEBPACKER_* → SHAKAPACKER_*, binstub path updated
bin/webpacker,bin/webpacker-dev-server	Deleted
bin/shakapacker,bin/shakapacker-dev-server	Generated via bundle exec rake shakapacker:binstubs
app/helpers/application_helper.rb	Added HAML-compatible javascript_pack_tag override

Stage 2: 7.2.3 to 8.4 (v8 upgrade guide)

File	Change
package.json	Added "packageManager": "yarn@1.22.22" field (required by v8)
package.json	Updated shakapacker 7.2.3 to 8.4.0
Gemfile	Updated shakapacker 7.2.3 to 8.4.0
Gemfile.lock	Updated with bundle update shackapacker ==conservative
yarn.lock	Updated with yarn install

Stage 3: 8.4 to 9.5 (v9 upgrade guide)

File	Change
Gemfile	Updated shakapacker 8.4.0 to 9.5.0
package.json	Updated shakapacker 8.4.0 to 9.5.0
Gemfile.lock	Updated with bundle update shackapacker ==conservative
yarn.lock	Updated with yarn install
config/shakapacker.yml	Added javascript_transpiler: babel (v9 defaults to SWC)
.semaphore/semaphore.yml	Changed webpacker:compile to shakapacker:compile

Type of change

• Bug fix
• New feature
• Enhancement
• Documentation
• Maintenance

Checklist

• I have tested these changes
• I have updated documentation as needed
• I have tagged the relevant people for review

Related Issues

Closes #4644

[aaccensi]

@noracato do the changes to docker-compose.yml made for in stage 1 need some action at CI/CD level? Ansible perhaps?

[louispt1]

Works well for me locally and seems reasonable!

I'm a bit unsure about the haml override - seems like something that might be an issue in the future but also not sure what we can do about it in the short term - maybe @noracato has ideas.

[louispt1]

Why babel?

[aaccensi]

Babel was the default javascript_transpiler before the bump but now it changed, so if we do not specify it it will use the new default (which is SWC). Their reason for the chance is because SWC is much faster so is not a trivial decision. For SWC we will need to install new dependencies and make sure nothing breaks if we remove that config, is all explained here.

[louispt1]

Ok seems out of scope for this PR then, interesting though!