Automate setting Collector release attributes as part of release job

When we create a release of Collector, we want the release job to:

• assign the date to the release-date
• assign the tag to release-dist-tag
• assign the SemVer to release-version

in antora.yml.

asciidoc:
  attributes:
    release-date: 2022-10-20
    release-dist-tag: latest
    release-version: '1.0.0-alpha.3'

In the future, like with Antora core, we'd like to fetch the node version. It would also be useful to have the release job identify the minimum Antora core version and assign it to an attribute such as core-minimum-version: '3.1' (and way in the future, the maximum Antora version when a Collector version is coming to EOL).

See antora#1011 (closed) for more information.