case insensitve intersection of curies

[rjawesome]

Allows input prefix to not have to be uppercase/lowercase (checks case agnostic). biothings/biothings_explorer#640

[codecov]

Codecov Report

Merging #151 (93904ee) into main (b102c55) will increase coverage by 6.14%.
The diff coverage is 57.89%.

@@            Coverage Diff             @@
##             main     #151      +/-   ##
==========================================
+ Coverage   60.81%   66.96%   +6.14%     
==========================================
  Files          26       26              
  Lines        2713     2712       -1     
==========================================
+ Hits         1650     1816     +166     
+ Misses       1063      896     -167     

Impacted Files	Coverage Δ
src/biolink.js	75.00% <ø> (-0.76%)	⬇️
src/cache_handler.js	82.73% <54.54%> (ø)
src/batch_edge_query.js	87.50% <57.14%> (+0.14%)	⬆️
src/query_node.js	83.80% <100.00%> (+19.04%)	⬆️

... and 10 files with indirect coverage changes

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