Start work on supporting filtering while parsing

[quinnj]

No description provided.

[codecov]

Codecov Report

Merging #656 into master will decrease coverage by 1.52%.
The diff coverage is 65.00%.

@@            Coverage Diff             @@
##           master     #656      +/-   ##
==========================================
- Coverage   84.47%   82.95%   -1.53%     
==========================================
  Files           8        8              
  Lines        1701     1748      +47     
==========================================
+ Hits         1437     1450      +13     
- Misses        264      298      +34     

Impacted Files	Coverage Δ
src/utils.jl	84.50% <ø> (ø)
src/file.jl	90.56% <63.91%> (-5.75%)	⬇️
src/rows.jl	93.22% <100.00%> (+0.05%)	⬆️

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[quinnj]

@NHDaly, sorry for the slightly random ping, but I'm actually diving back in to the code here and want to make a push. would you mind taking a look here if you have a moment? Happy to jump on a quick call too if that'd be easier to do a quick review of what's going on here.