Add linter doctests

[ReubenJ]

All changes in src and test are a result of running the formatting script.

[codecov]

Codecov Report

Attention: Patch coverage is 69.67742% with 47 lines in your changes missing coverage. Please review.

Project coverage is 45.98%. Comparing base (97b0e62) to head (8ed6fc2).
Report is 20 commits behind head on master.

Files with missing lines	Patch %	Lines
src/rulenode_operators.jl	22.58%	24 Missing ⚠️
src/grammar_base.jl	57.89%	8 Missing ⚠️
src/utils.jl	0.00%	8 Missing ⚠️
src/csg/csg.jl	81.81%	6 Missing ⚠️
src/grammar_io.jl	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #87      +/-   ##
==========================================
+ Coverage   45.95%   45.98%   +0.03%     
==========================================
  Files           8        8              
  Lines         457      461       +4     
==========================================
+ Hits          210      212       +2     
- Misses        247      249       +2     

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[ReubenJ]

Closing in favor of BestieTemplate.