Have term search use .raw field, alert user when query filter syntax is malformed

[nagem]

Review Checklist

• Tests were added to cover all code changes
• Documentation was added / updated
• Code and tests follow standards in CONTRIBUTING.md

[codecov-io]

Codecov Report

Merging #950 into master will decrease coverage by 0.05%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #950      +/-   ##
==========================================
- Coverage    90.1%   90.04%   -0.06%     
==========================================
  Files          48       48              
  Lines        6465     6471       +6     
==========================================
+ Hits         5825     5827       +2     
- Misses        640      644       +4

Flag	Coverage Δ
#python	90.04% <50%> (-0.06%)	⬇️

Impacted Files	Coverage Δ
api/handlers/dataexplorerhandler.py	82.49% <50%> (-1.18%)	⬇️

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[kofalt]

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