Refactor Bazel unit test CI

[aaronmondal]

Unify workflows for Unix and Windows and use more efficient caching for workflow artifacts. Harden the workflow with fixed action hashes.

Reduces Linux workflow runtime to ~1 min for best-case cache hits.

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This change is 

[aaronmondal]

FYI cache reuse runtimes are in the workflows here (the ones that take ~50 seconds 😈) aaronmondal#3

[allada]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @aaronmondal and @MarcusSorealheis)

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.github/workflows/unit-test.yaml line 50 at r1 (raw file):

        run: |
          if [ "$RUNNER_OS" == "Linux" ] || [ "$RUNNER_OS" == "macOS" ]; then
            bazel test ...

nit: bazel test //...

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.github/workflows/unit-test.yaml line 56 at r1 (raw file):

              test \
              --config=windows \
              ...

nit: //...

[aaronmondal]

Reviewable status: 1 of 2 files reviewed, all discussions resolved (waiting on @allada and @MarcusSorealheis)

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.github/workflows/unit-test.yaml line 50 at r1 (raw file):

Previously, allada (Nathan (Blaise) Bruer) wrote…

nit: bazel test //...

Done. Ah damn I prefer the ... syntax much more, but there can be compatibility issues with some shells (I believe zsh) that interpret triple dots in a different way. So the //... is the more compatible way to go 😞