[Feature] Automate changelog generation for non-alpha/beta releases

[narin]

Ticket #7053

Description of Change

• Adds changelog generation to publish workflow using github-changelog-generator
• Changelogs will be generated using the titles of PRs merged since the last tag. Note: when we eventually move our issues to a separate ZenHug instance, we'll be able to generate changelogs based on closed issues instead.
• Generates changelog for the specified package being published
• Filters out alpha and beta tags
• Adds setup-ruby step, Gemfile, and Gemfile.lock for caching
• Update PR template for clearer PR naming suitable for changelogs

Testing Packages

components-v0.2.2-alpha.0...21

Screenshots/Video

Testing

• Tested on GHA

PR Checklist

Code reviewer validation:

• General
  • PR is linked to ticket(s)
  • Acceptance criteria:
    • All satisfied or
    • Documented reason for not being performed or
    • Split to separate ticket and ticket is linked by relevant AC(s)
  • Above PR sections adequately filled out
  • If any breaking changes, in accordance with the pre-1.0.0 versioning guidelines: a CU ticket has been created for the VA Mobile App detailing necessary adjustments with the package version that will be published by this ticket
• Code
  • Tests are included if appropriate (or split to separate ticket)
  • New functions have proper TSDoc annotations

Publish

If changes warrant a new version per the versioning guidelines and the PR is approved and ready to merge:

• Merge main into branch
• Publish new version
• Merge branch to main