Check for RR field presence before merging RR to eCR

[emmastephenson]

PULL REQUEST

Summary

Checks to see if RR data has already been extracted and inserted into the eCR before merging RR data into eCR. (Basically - have we already called this method?)

Related Issue

Fixes #844

Additional Information

Debated for a bit about raising a ValueError instead of just returning the eCR values, but this seemed cleaner - there's no need for the caller to know they called the method with a pre-merged eICR.

[codecov]

Codecov Report

Merging #866 (6e79e0e) into main (397f6e8) will decrease coverage by 0.04%.
Report is 2 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #866      +/-   ##
==========================================
- Coverage   96.40%   96.37%   -0.04%     
==========================================
  Files          46       46              
  Lines        2645     2648       +3     
==========================================
+ Hits         2550     2552       +2     
- Misses         95       96       +1     

Flag	Coverage Δ
unit-tests	96.37% <100.00%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
phdi/fhir/conversion/convert.py	99.12% <100.00%> (+0.02%)	⬆️

... and 1 file with indirect coverage changes

[BradySkylight]

Everything looks good, but it may be better to search for the specific code ("2.16.840.1.113883.6.1"), rather than looking for text. But, either way, it should technically work.

[BradySkylight]

Awesome work!