Add an action and a GitHub workflow to get release notes via GitHub and prepare release content.

[eason9487]

Changes proposed in this Pull Request:

This PR implements part 1 in #15 - 📌 Prepare a release content when a specific branch is created onto the target revision.

• Move some functions to the utils directory.
• Add generateReleaseNotes method to RepoTool class.
• Add a new util getPackageSettings for getting the settings of package.json.
• Add a new custom GitHub action for getting release notes via a GitHub API, and infer the next version and tag.
• Add a new GitHub workflow to prepare a new release for the GitHub actions package.
• Update docs for get-release-notes action and release process.

Before merge:

• Delete release/actions-demo-1 and release/actions-demo-2 branches.
• Clean up test branches if any.

Detailed test instructions:

Check simulations on Actions

💡 Since this workflow is not easy to test, I created two simulations to demonstrate the results. And two merged PRs (#11 and #12) were attached to the [actions] changelog: add label for grouping the changelog to match the version level.

1. The first one shows the initial release - workflow result
   • For the first-time release, it won't bump the versions and will use the version value in package.json as the initial release version number.
     
   • View the changes committed by the "Prepare New Release" workflow.
2. The second one simulates the version bumping and the second changelog prepending - workflow result
   • For the subsequent release, it bumps the versions based on the version value in package.json, and increases the version level by matching the level keywords to the changelog content.
   • In this demo, the content has a ### New Features 🎉 heading that matches the minor level. So the next version is 1.1.0.
   • View the changes committed by the "Prepare New Release" workflow to check if the versions were updated.

Test the release preparation by creating the release branch

1. Create release/actions branch based on this PR. https://github.com/woocommerce/grow/tree/add/prepare-release-action
   
2. Go to the "Prepare New Release" workflow to see how it goes.

The release/actions-demo-1 and release/actions-demo-2 won't trigger the workflow. They were originally the release/actions branch, and I renamed them to keep the demo results.

Changelog entry

[tomalec]

🚧 If we remove the PR authors and links, I think we should also remove the

## New Contributors

section. (See https://github.com/woorelease-bugs/initial-release/releases/new?tag=1.0.1 fro an example)

[eason9487]

The outputs.release-changelog output only contains the part of "## What's Changed" heading and its entries. So other contents won't be included. I added output logs in the get-release-notes action by dd0226a. It should be easier to know the actual values of outputs and to use them.

[tomalec]

Ah, ok, now I got it.
/## What's Changed\n([\d\D]+?)(?=\n\n)/i catches all the things before the double line break => before

##New Constributors

[tomalec]

Great tool, thanks!
Reviewed the code, and inspected workflow logs - LGTM.

The only comments I have are:

• 🚧 https://github.com/woocommerce/grow/pull/16/files#discussion_r902845866
• 💅 that maybe we don't need that much granularity between feature/update/enhancement and we can keep only two. But, I'm fine with all three as well to keep it consistent with bigger projects. Plus we could always change it later.

[eason9487]

@tomalec, thanks for the review.

• that maybe we don't need that much granularity between feature/update/enhancement and we can keep only two. But, I'm fine with all three as well to keep it consistent with bigger projects. Plus we could always change it later.

I adjusted the config of release notes in fc88a06. By the way, after some tests, the bot accounts like dependabot don't have the [bot] suffix when setting the exclude list in the config.

Could you help with a new round of code reviews?

[tomalec]

LGTM :) thanks