Set up a smoke screen test before the full matrix is run

[ViralBShah]

I often see PRs running the full matrix and all of them failing. I almost wonder if there is a way, such that we run one CI test (say ubuntu-latest, x64, latest stable release), and run the full matrix only after that passes (and ideally not re-running that one).

Would probably help save quite a bit on CI running time.

[DilumAluthge]

Sounds like a good idea. It should be relatively easy to implement. I can take a look at some point, although I probably won't have a chance to get to it this week.

[LilithHafner]

I recently set this up over at Chairmarks: https://github.com/LilithHafner/Chairmarks.jl/blob/87a758749b86b047efe10719fda10efd4781ee56/.github/workflows/CI.yml#L23

Basically you have one job that runs one test and then after that a matrix with a "needs: " clause. The matrix can have an "exclude: " entry for the configuration already run (my matrix is fully unrolled because I want it to be sparse). This is something that is pretty easy to do at the repository level but would be tricky to put into the setupjulia action. Perhaps it would be more appropriate to add it to PackageTemplates and make PRs to existing packages.

There's also the failfast strategy for matrix runs which would be similar.

[ViralBShah]

@LilithHafner Would it be possible to set that up on Example.jl? At least I use that as a reference repo to copy common configurations from into existing packages. PkgTemplates would be great for new packages.

[LilithHafner]

Done.