Add options to filter out internal GC and dispatch frames

[NHDaly]

The GC frames are skipped by default now, since they make the GC graphs much less readable, and everyone basically always wants them skipped.

I also refactored things a bit in the process, to allow for only checking these once per frame, and caching the result.

This gives nicer graphs like this one, where the recursion here is real - this is a profile of julia's inference:

or this one:

I also added this message to tell you about the new flags

[codecov-commenter]

Codecov Report

Merging #87 (c53b14b) into main (8764c85) will increase coverage by 0.39%. The diff coverage is 100.00%.

:exclamation: Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

@@            Coverage Diff             @@
##             main      #87      +/-   ##
==========================================
+ Coverage   96.59%   96.99%   +0.39%     
==========================================
  Files           3        3              
  Lines         294      333      +39     
==========================================
+ Hits          284      323      +39     
  Misses         10       10              

Files Changed	Coverage Δ
src/Allocs.jl	93.54% <100.00%> (+1.34%)	:arrow_up:
src/PProf.jl	99.31% <100.00%> (+0.13%)	:arrow_up:

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more