[9.18] new: ci: Add tarball publication process to pipeline

[9.18] new: ci: Add tarball publication process to pipeline

Tarball uploading steps are to be included in the pipeline.

They are manual jobs that:

1. uploads a release tarball prepared by the "sign" job.
2. publish a previously staged release to a destination.
3. publishes a previously staged release to a well-known URL.

A template has been included since all three follow the same pattern.
Besides, rules commonly used by tag pipeline jobs.

Backport of MR !11158

Merge branch 'backport-andoni/ci-release-process-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!11161