RFR: 8254691: Enable GitHub actions for jfx repo

[Kevin Rushforth]

On Mon, 26 Oct 2020 08:29:14 GMT, Robin Westberg <rwestberg at openjdk.org> wrote:

>> The jdk workflow is split into a build job and multiple test jobs (since it takes so long they need the parallelism when running the tests). It's more complicated that way, since you have to feed the results of the build job into all of the test jobs, and there is duplication of some of the configuration steps. I don't know that it would buy us much, so I wasn't planning to split the jobs -- at leat not initially.
>> 
>> The build and test are done in separate steps within the job so it's easy to see which one failed. Maybe Robin can comment further as to whether we could do something a bit more clever.
>
>> I noticed this in the openjdk/mobile repository as well, and that looks great. In that repository, there seems to be a different configuration, as there is a line for "build" and a line for "test/tier 1" ( e.g. [openjdk/mobile#10](https://github.com/openjdk/mobile/pull/10) )
>> 
>> I wonder how configurable this is?
> 
> The output is not very configurable at all. :) You can see https://github.com/openjdk/skara/blob/bd4cc7e9a6ff7b04c6dc650a969638d5c1471031/bots/pr/src/main/java/org/openjdk/skara/bots/pr/TestResults.java#L42 for details. But it should support additional tiers at least if any were added in the future.

### Note to reviewers:

If you want to test this yourself you can pull the PR branch into a branch in your local repo and push it to your personal fork. Something like the following should work for you, assuming that you are in your local repo with `origin` pointing to your personal fork:

git fetch https://github.com/openjdk/jfx.git pull/338/head:pr-338
git push -u origin pr-338

Then you will be able to see the GitHub action workflow and track its progress by clicking on the "Actions" tab on your personal fork repo page.

-------------

PR: https://git.openjdk.java.net/jfx/pull/338