Update HTTPAPI handlers to return non-200 status codes when errors occur (SYN-8734)

[vEpiphyte]

• Errors sent by HTTP APIs ( via sendRestErr / sentRestExc ) now have non-200 HTTP status codes sent. These errors still contain valid JSON in their responses.
• Storm APIs will now catch errors and return a non-200 status code when a query execution precondition fails; so users can now better distinguish failures from a successful query.
• Added status_code keyword only arguments to sendRestRetn / sendRestErr / sendRestExc
• sendRestExc now pulls a mesg from SynErr errors before relying on str(e).
• Changed HTTP codes in handlers and tests to use the stdlib http.HTTPStatus enum

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.29%. Comparing base (380275b) to head (780f4f5).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4169      +/-   ##
==========================================
- Coverage   97.35%   97.29%   -0.07%     
==========================================
  Files         261      261              
  Lines       59877    59894      +17     
==========================================
- Hits        58294    58273      -21     
- Misses       1583     1621      +38     

Flag	Coverage Δ
linux	97.29% <100.00%> (+<0.01%)	⬆️
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[MichaelSquires]

Most of the requested changes are integers to http.HTTPStatus.XXX codes.