CHEF-37441: Add ~/.chef/ruby/VERSION/gems to GEM_PATH for dynamic plugin loading

[sanghinitin]

Summary

Ensures gems installed via chef gem install knife-<plugin> are immediately discoverable by knife at runtime, without requiring any additional configuration.

Problem

chef-cli gem install places gems under ~/.chef/ruby/<RUBY_API_VERSION>/gems (e.g. ~/.chef/ruby/3.4.0/gems). This path was not included in the GEM_PATH used by the knife binstubs or the Habitat runtime wrapper, so plugins such as knife-azure were invisible to knife even after knife rehash.

Changes

• binstub_patch.rb — prepend three paths to GEM_PATH at binstub startup:
  1. Package vendor dir (knife's bundled deps — was already present)
  2. Gem.user_dir → ~/.gem/ruby/VERSION (standard gem install)
  3. ~/.chef/ruby/VERSION/gems via RbConfig::CONFIG['ruby_version'] (chef-cli gem install)
• habitat/plan.sh — runtime knife wrapper exports expanded GEM_PATH including ${HOME}/.gem/ruby/${ruby_gem_version} and ${HOME}/.chef/ruby/${ruby_gem_version}/gems
• habitat/aarch64-darwin/plan.sh — same GEM_PATH additions for macOS ARM64
• habitat/plan.ps1 — two Windows fixes:
  • Pass --ignore-dependencies to gem install knife*.gem to avoid appbundler ambiguous specs errors
  • Inject binstub_patch.rb into generated binstubs after appbundler.bat, mirroring the Linux/macOS sed approach

Evidence

$ chef-cli gem info knife-azure
*** LOCAL GEMS ***
knife-azure (4.0.0)

Installed at: /Users/home/.chef/ruby/3.4.0/gems

With this change, knife resolves plugins from that path at launch.

Files Modified

• binstub_patch.rb
• habitat/plan.sh
• habitat/aarch64-darwin/plan.sh
• habitat/plan.ps1