Fix Extended Instant

[alexanderkiel]

ExtendedInstant could not handle null values. So it wasn't possible to import resources with instants without a value. I added transaction tests with a diagnostic report containing an issued instant.

[codecov]

Codecov Report

Merging #984 (2f82a0e) into develop (e43d296) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #984   +/-   ##
========================================
  Coverage    94.12%   94.13%           
========================================
  Files          238      238           
  Lines        15233    15237    +4     
  Branches       380      379    -1     
========================================
+ Hits         14338    14343    +5     
  Misses         515      515           
+ Partials       380      379    -1     

Impacted Files	Coverage Δ
...dules/rest-api/src/blaze/rest_api/capabilities.clj	96.29% <ø> (ø)
...laze/db/impl/index/search_param_value_resource.clj	100.00% <100.00%> (ø)
modules/db/src/blaze/db/impl/search_param/date.clj	97.50% <100.00%> (-0.07%)	⬇️
...odules/fhir-structure/src/blaze/fhir/spec/type.clj	86.33% <100.00%> (+0.04%)	⬆️

... and 1 file with indirect coverage changes