Implement FinalizerEscape

[jpsamaroo]

With the intention of eventually using this to add early finalize calls to minimize GC overhead of functions with many large-but-temporary heap allocations with finalizers.

[codecov-commenter]

Codecov Report

Merging #90 (e48ce37) into master (4bd18e1) will decrease coverage by 0.81%.
The diff coverage is 32.14%.

❗ Current head e48ce37 differs from pull request most recent head d687586. Consider uploading reports for the commit d687586 to get more accurate results

@@            Coverage Diff             @@
##           master      #90      +/-   ##
==========================================
- Coverage   80.02%   79.21%   -0.82%     
==========================================
  Files           3        3              
  Lines        1382     1400      +18     
==========================================
+ Hits         1106     1109       +3     
- Misses        276      291      +15     

Impacted Files	Coverage Δ
src/EAUtils.jl	43.40% <0.00%> (-0.73%)	⬇️
src/EscapeAnalysis.jl	85.17% <36.00%> (-0.85%)	⬇️

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[aviatesk]

So how FinalizerEscape can be used? If we insert finalize call for allocations whose FinalizerEscape is true, we will end up inserting early finalize calls for anything escaping (since AllEscape also has FinalizerEscape=true.

[jpsamaroo]

Should FinalizerEscape=true not be part of AllEscape?

My initial thoughts were that if nothing escaped other than the object being finalized, and the object being finalized does not otherwise escape, then we'd insert finalize at the end of the liveness range.