Add unmeasured amounts to proto

[connorcoley]

Fixes #605

• Added to the proto
• Added to the build_compound helper function with a corresponding test
• Validations are not complex; the oneof handles mutual exclusivity of fields already. I also added a special warning if a compound is SATURATED but it is in an input without another compound. There is a new test for this as well
• Added to visualization's filters.py and added an unmeasured amount to the test reaction used there

I think these are all of the changes necessary, but please let me know if I'm forgetting something @skearnes

[codecov[bot]]

Codecov Report

Merging #610 (bf806e0) into main (e228d70) will increase coverage by 0.24%. The diff coverage is 90.47%.

@@            Coverage Diff             @@
##             main     #610      +/-   ##
==========================================
+ Coverage   76.19%   76.44%   +0.24%     
==========================================
  Files          18       18              
  Lines        1941     1953      +12     
  Branches      480      485       +5     
==========================================
+ Hits         1479     1493      +14     
+ Misses        314      313       -1     
+ Partials      148      147       -1     

Impacted Files	Coverage Δ
ord_schema/message_helpers.py	84.25% <81.81%> (+0.07%)	:arrow_up:
ord_schema/validations.py	70.39% <100.00%> (+0.34%)	:arrow_up:
ord_schema/visualization/filters.py	61.23% <100.00%> (+1.30%)	:arrow_up: