profile: Add heap snapshot profiling support #75

Job	Run time
Julia 1 - ubuntu-latest - x64	12m 4s
Test with `JETLS_DEBUG_LOWERING = true`	14m 40s
Julia 1 - macos-latest - x64	15m 23s
Julia nightly - ubuntu-latest - x64	3m 33s
Julia 1.12 - ubuntu-latest - x64	12m 6s
Test with `JETLS_DEV_MODE = true`	12m 3s
Test with `JULIA_NUM_THREADS = 4,2`	11m 59s
Test jetls executable	6m 17s
	1h 28m 5s

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