Use bun for installation if applicable

[terracatta]

This PR is part of an overall effort to allow Rails developers to completely use the Bun JS runtime and bundler without needing to use Node.JS and Yarn.

This gem is automatically invoked when a new rails projects is created and before this PR would always use Yarn. After this PR this gem will detect which JS bundler is being used and use the correct one so that Yarn doesn't accidentally slip into your Rails project.

I have opened a companion PR to the stimulus-rails repo as well.

Example run of javascript:install:bun and bin/rails turbo:install

☁  test_app [main] ./bin/rails javascript:install:bun
Compile into app/assets/builds
      create  app/assets/builds
      create  app/assets/builds/.keep
      append  app/assets/config/manifest.js
      append  .gitignore
      append  .gitignore
Add JavaScript include tag in application layout
      insert  app/views/layouts/application.html.erb
Create default entrypoint in app/javascript/application.js
      create  app/javascript
      create  app/javascript/application.js
Add default package.json
      create  package.json
Add bin/dev to start foreman
      create  bin/dev
Add default Procfile.dev
      create  Procfile.dev
Ensure foreman is installed
         run  gem install foreman from "."
Successfully installed foreman-0.87.2
Parsing documentation for foreman-0.87.2
Done installing documentation for foreman after 0 seconds
1 gem installed
Add default bun.config.js
      create  bun.config.js
Add build script to package.json

☁  test_app [main] ⚡  bin/rails turbo:install
Import Turbo
      append  app/javascript/application.js
Install Turbo
         run  bun add @hotwired/turbo-rails from "."
bun add v1.0.0 (822a00c4)

 installed @hotwired/turbo-rails@7.3.0


 3 packages installed [2.01s]
Run turbo:install:redis to switch on Redis and use it in development for turbo streams

[seanpdoyle]

@afcapel are you able to review this? It might be time-sensitive see this comment and this one too.

[afcapel]

Thanks @terracatta

[terracatta]

Thanks @afcapel are you able to do a similar review for hotwired/stimulus-rails#125 ?

[1st8]

Just saying: This needs to released to make rails new --js bun work with rails 7.1.0.rc1.

Currently turbo-rails runs yarn add, which generates a yarn.lock, which then makes cssbundling-rails also use yarn.

When using --skip-hotwire bun is used correctly.

Uses bun correctly: rails new --js bun --css tailwind --skip-hotwire bun_rails
Erroneously uses yarn: rails new --js bun --css tailwind bun_rails

[terracatta]

cc/ @dhh any possibility you can cut a release for this gem before 7.1.0 final is out?

Can you also merge hotwired/stimulus-rails#125 can cut a release for stimulus-rails?

This will be the only way to ensure the new rails new --js bun option will work.

[ghiculescu]

@dhh bump on this ^

ref: rails/rails#49522

[dhh]

cc @afcapel