Release automation update (for unstable)

[Peter-Sh]

This PR includes changes for the release automation (from release/8.4) with conflict resolution for unstable branch.

Changes

For unstable builds special release_tag=unstable value were introduced.

Makefile modifications are moved to build-source-package action which is aware of 'unstable' release_tag.

Upload actions do uploads for internal and public releases to different s3 buckets.

If there is a release_tag and upload is successful

• A release version branch is merged into mainline branch (8.4.1 --> release/8.4)
• A tag v8.4.1 is created

Slack nofitications

• When build fails (for non empty and non unstable release_tag)
• When upload fails
• When upload succeeds

Changes in workflow files

apt.yml used only for PR and unstable and don't include upload.

build-n-test-all-distros.yml - reusable workflow for doing src and binary build and smoke tests

Two workflows for release automation
release_build_and_test.yml
release_publish.yml

Workflow split into actions:

build-binary-package - Builds binary packages for multiple architectures
build-source-package - Creates source packages for different distributions
bump-debian-changelog - Automatically updates Debian changelog for releases
parse-release-handle - Parses release metadata from JSON inputs
run-smoke-tests - Executes smoke tests on built packages
slack-notification - Sends formatted notifications to Slack
upload-packages - Uploads packages to S3 repositories