Support process execution using URL encoded KVP query parameters

[fmigneault]

Description

Similar to older WPS Execute, but using new OGC-API - Processes definitions, add support of
GET request on /proceses/{processId}/execution endpoint using KVP for inputs definition.

Notes

• Using support XML WPS-like requests from OGC-API REST endpoint #455, XML POST supports WPS-like Execute. Only GET with KVP not yet supported.
  KVP on REST-API endpoint will not behave exactly like WPS endpoint KVP since I/O can contain slightly different (cardinality/array) definitions.

• KVP are defined as an extension of core OGC-API - Processes, it is not mandatory

Implementation

• handle input literal passed directly <inputId>=<value>
• handle input complex passed by value (URL-encoded)
• handle input passed by reference <inputId>[href]=<url> and <inputId>[type]=<media-type>
• handle output desired format <outputId>[mediaType]=...
  • must consider pre-requirement of <outputID>[include]=true to distinguish outputs from <inputId>=...
    (see https://github.com/opengeospatial/ogcapi-processes/blob/master/core/requirements/kvp-execute/REQ_output.adoc)
• input cardinality
  • must consider nested arrays as URL encoded values
    (see https://github.com/opengeospatial/ogcapi-processes/blob/master/core/requirements/kvp-execute/REQ_input-cardinality.adoc)
• bbox with CRS control (see: Conflicting KVP execute parameters opengeospatial/ogcapi-processes#402)
• handle f and prefer (see: Conflicting KVP execute parameters opengeospatial/ogcapi-processes#402)
• other requirements: https://github.com/opengeospatial/ogcapi-processes/blob/master/core/sections/clause_15_kvp-execute.adoc
• conformance for KVP execution #607

References

• Add support for URL-encoded execute requests (Issue 96) opengeospatial/ogcapi-processes#290
  main document: https://github.com/opengeospatial/ogcapi-processes/pull/290/files#diff-815d59378087ebec109c7711fe5266f43a0f2a30cb8d01b2444cc79f03fe419f