profile: Add heap snapshot profiling support (#355) #77

Job	Run time
Julia nightly - ubuntu-latest - x64	3m 32s
Julia 1 - macos-latest - x64	17m 35s
Julia 1 - ubuntu-latest - x64	12m 8s
Test with `JETLS_DEV_MODE = true`	12m 38s
Test jetls executable	6m 25s
Test with `JETLS_DEBUG_LOWERING = true`	14m 39s
Test with `JULIA_NUM_THREADS = 4,2`	14m 44s
Julia 1.12 - ubuntu-latest - x64	11m 58s
	1h 33m 39s

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