add propertynames for PosLen

[KristofferC]

this allows tab completion

julia> p = Parsers.PosLen(1, 1, false, false);

julia> p.<TAB>
escapedvalue  len           missingvalue  pos

[codecov]

Codecov Report

Merging #121 (fd8e7f9) into main (b1da070) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #121      +/-   ##
==========================================
- Coverage   87.70%   87.66%   -0.04%     
==========================================
  Files           9        9              
  Lines        2309     2310       +1     
==========================================
  Hits         2025     2025              
- Misses        284      285       +1     

Impacted Files	Coverage Δ
src/utils.jl	90.35% <0.00%> (-0.47%)	⬇️

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[nickrobinson251]

Thanks!

[quinnj]

Good catch!