Color constprop-nodes in flamegraph

[timholy]

Constant-propagation can be an unexpected source of recompilation, so it makes sense to highlight it. This piggy-backs off of FlameGraph's marking of GC-events (default coloration yellow) to mark nodes where one or more non-function arguments has constant-propagation.

TODO:

• [x] update docs

[codecov[bot]]

Codecov Report

Merging #272 (92b457d) into master (d18b722) will decrease coverage by 4.40%. The diff coverage is 88.88%.

:exclamation: Current head 92b457d differs from pull request most recent head 291c7d8. Consider uploading reports for the commit 291c7d8 to get more accurate results

@@            Coverage Diff             @@
##           master     #272      +/-   ##
==========================================
- Coverage   86.87%   82.47%   -4.41%     
==========================================
  Files          16       16              
  Lines        2004     1900     -104     
==========================================
- Hits         1741     1567     -174     
- Misses        263      333      +70     

Impacted Files	Coverage Δ
src/parcel_snoopi_deep.jl	87.72% <88.88%> (-1.85%)	:arrow_down:
src/invalidation_and_inference.jl	0.00% <0.00%> (-100.00%)	:arrow_down:
src/invalidations.jl	87.04% <0.00%> (-3.12%)	:arrow_down:
src/deep_demos.jl	57.89% <0.00%> (-1.08%)	:arrow_down:
src/write.jl	91.30% <0.00%> (-1.01%)	:arrow_down:
src/parcel_snoopl.jl	89.47% <0.00%> (-0.53%)	:arrow_down:
SnoopCompileCore/src/snoopi_deep.jl	91.66% <0.00%> (-0.34%)	:arrow_down:
src/parcel_snoopi.jl	93.83% <0.00%> (-0.31%)	:arrow_down:
src/visualizations.jl	0.00% <0.00%> (ø)
... and 1 more

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[timholy]

This was used to identify targets for https://github.com/JuliaLang/julia/pull/43367