Rework GitHub Release and Docker Actions

[FlyGoat]

The universal goal is to make those actions available in forks, remove some cumbersome scripts and unnecessary steps, enable arm64 build and upload to ghcr.io as an alternative container registry.

Docker pushing/tagging policy is remaining unchanged.

For an example release run: https://github.com/FlyGoat/opengrok/actions/runs/14887002399 (Triggered by release 99.1.3)

Which produced: https://github.com/FlyGoat/opengrok/pkgs/container/opengrok and https://hub.docker.com/r/flygoat/opengrok

Also fixes #3948.

Thanks!

[oracle-contributor-agreement[bot]]

Thank you for your pull request and welcome to our community! To contribute, please sign the Oracle Contributor Agreement (OCA). The following contributors of this PR have not signed the OCA:

• PR author: [email protected] (@FlyGoat)

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[FlyGoat]

OCA already signed, seems pending approval.

[FlyGoat]

Note that Docherhub's repository is set via DOCKER_SLUG repository variable. For this repo please set it to opengrok/docker before merge.

It should be set at: https://github.com/oracle/opengrok/settings/variables/actions

See also: https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables

[oracle-contributor-agreement[bot]]

Thank you for signing the OCA.

[FlyGoat]

Hi @vladak, This PR is ready.

I really wish to see an official arm64 docker release :-)