Fix XML Output for Resources with Control Chars

[alexanderkiel]

If resources contain control characters like \u001e (record separator) in strings or other string like primitive type values, the XML generator can't output them. Because the resulting exception is not handled, the output hangs and will never finish.

Closes: #1552

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.90%. Comparing base (a820081) to head (8a81f5a).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1553   +/-   ##
========================================
  Coverage    95.89%   95.90%           
========================================
  Files          246      246           
  Lines        15903    15908    +5     
  Branches       332      331    -1     
========================================
+ Hits         15250    15256    +6     
  Misses         321      321           
+ Partials       332      331    -1     

Files	Coverage Δ
...odules/fhir-structure/src/blaze/fhir/spec/impl.clj	95.90% <100.00%> (ø)
...odules/fhir-structure/src/blaze/fhir/spec/type.clj	84.38% <100.00%> (+0.18%)	⬆️
...fhir-structure/src/blaze/fhir/spec/type/system.clj	97.72% <100.00%> (ø)
.../rest-api/src/blaze/rest_api/middleware/output.clj	100.00% <100.00%> (ø)