more CI workflow files refactoring #1

Job	Run time
Julia 1.12 - ubuntu-latest - x64	14m 45s
Test with `JULIA_NUM_THREADS = 4,2`	15m 7s
Test with `JETLS_DEBUG_LOWERING = true`	14m 45s
Julia 1 - macos-latest - x64	21m 53s
Julia 1 - ubuntu-latest - x64	14m 55s
Test with `JETLS_DEV_MODE = true`	14m 21s
Julia nightly - ubuntu-latest - x64	3m 50s
Test jetls executable	6m 33s
	1h 46m 9s

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