GIthub workflow for jre4temper repo

[ben-509]

Laying out some requirements:

• This comment summarizes the steps to build a JRE release.
  • It's a gradle task, so nothing complicated there.
• Then those assets need to be saved somewhere
  • The jre4temper repo is set up to accept releases.
• The release-dev workflow needs to pick up the appropriate assets.
  • Right now it's a wget with some environment variables.
  • Seems like we could simply add a manifest to the assets.
• The release-dev workflow needs to configure its test matrix.
  • We can use outputs from a prior job to configure it. (Example)
  • Thus our manifest can also configure the matrix.

[ben-509]

As to running it, if we have a monthly job that finds the latest minor versions of JREs using sdkman or something like that, it'd be fine.

Another point to test out: The prebake will need to run on various runners, each of which generates local artifacts. Then a combiner job pulls those together, builds a manifest, and plonks it all in jre4temper.

[tjpalmer]

@ben-509 Is this issue done?