Ignore Unknown Values of the _summary Search Param

[alexanderkiel]

Also make use of multiple _elements parameters.

Closes: #1863

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.68%. Comparing base (c876040) to head (588690d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1868      +/-   ##
==========================================
- Coverage   94.70%   94.68%   -0.02%     
==========================================
  Files         320      320              
  Lines       19246    19254       +8     
  Branches      477      479       +2     
==========================================
+ Hits        18226    18230       +4     
- Misses        543      545       +2     
- Partials      477      479       +2     

Files	Coverage Δ
...nteraction/src/blaze/interaction/search/params.clj	100.00% <100.00%> (ø)
modules/rest-util/src/blaze/handler/fhir/util.clj	99.59% <100.00%> (ø)

... and 2 files with indirect coverage changes