Automate dev portal controller release

[Patryk-Stefanski]

Description

This PR introduces an automated release workflow for the Developer Portal Controller, streamlining the release process with GitHub Actions.

Changes

• automated-release.yaml: New workflow that can be triggered manually to prepare a release. It validates semver format, creates/uses release branches (e.g., release-v0.1), updates the VERSION in the Makefile, and opens a PR for review.
• release.yaml: New workflow that triggers automatically when a release PR is merged. It creates and pushes the git tag, determines if it's a prerelease (alpha/beta/rc), generates release notes from the GitHub API, and creates the GitHub Release.
• github-release-changelog.sh: Utility script that calls the GitHub API to auto-generate release notes by comparing with the previous release tag.
• RELEASE.md: Documentation covering the release process including:
  • How to use the automated workflow (recommended)
  • How to create patch releases via cherry-picking
  • Manual release steps as a fallback
• Makefile: Minor update to set VERSION ?= 0.0.0 as the placeholder on main branch (actual version is set on release branches).

[eguzki]

Looks good. Just one comment.

When the tag already exists, the workflow skips the steps silently. This means the workflow succeeds without performing any actions. We could configure the workflow to fail instead; however, someone would then need to remove the existing tag manually. Alternatively, we can check if the current commit is indeed the one being tagged. If it is, we can proceed with the release generation. Thoughts?

[eguzki]

LGTM

Nice work 👍