Create a CHANGELOG.md before publishing extension update

[snutij]

Motivation

Closes Shopify/ruby-lsp#1645

The need is to create a CHANGELOG.md (without manual intervention) packaged into the extension publish.

Implementation

• Retrieve all releases (including last one as this workflow is trigger after the release)
• Keep tag version and body (content of the release note)
• Prepend a # before the tag to make a clear separation in the markdown between each release
• Insert this into a CHANGELOG.md at the root level as required by the specification

Automated Tests

Impossible as I can't publish it myself.

Manual Tests

I did a test, adding this code in the ci.yml workflow to check that everything goes as expected on push on my fork.
Result is available here: https://github.com/snutij/vscode-ruby-lsp/actions/runs/6344046810/job/17233282072

• ls output show the root level with the CHANGELOG.md
• cat CHANGELOG.md show the output well formatted

Note: we can see before each release note content this <!-- Release notes generated using configuration in .github/release.yml at main --> but we don't care as this is a comment it should not be displayed into vscode extension changelog tab.

I'll not copy-past output here, because it will link this PR to all PR already merged 😄

[vinistock]

Instead of using curl, let's use github-script.

We can fetch only the latest release directly and I'm sure the release's ID or tag must be present in the action's context object. That way we don't need to use curl or jq.

[snutij]

Yes we can but doing that CHANGELOG will include only lastest release information. Is it the expected behavior?

[vinistock]

That's a good point. It probably makes more sense to include everything. Let's still use github-script if possible though.

[snutij]

Done, and tested with ci.yml workflow again: https://github.com/snutij/vscode-ruby-lsp/actions/runs/6364070663/job/17280102315

[vinistock]

Very nice. Thank you for putting this together and testing it!