Add circe json to Capr serialization

[mdlavallee92]

Be able to coerce a circe json into a capr format. Use case is Capr allows for easier "quick" edits of a definition programatically.

See #101 this is the same feature request. @azimov also requested

Use case code:

# import circe json and coerce into Capr
cd <- readInCirce(path = "my_complex_cohort.json")
# add an inclusion rule into my cohort
cd@attrition@rules[[3]] <- withAll(
      exactly(1,
              observationPeriod(),
              duringInterval(eventStarts(-Inf, -365), eventEnds(-1, Inf))
      )
    )

[mdlavallee92]

Status: @azimov if you want to help

Added new file called toCapr.R. In here add internal functions for readInCirce. See old capr code for original version of circe to capr.

• Convert concept sets to Capr
• convert query attributes to Capr attributes
• add source concept attribute
• convert correlated criteria attribute
• convert query to Capr query with domain
• convert circe count to Capr criteria
• convert circe group to Capr group
• convert primary criteria to Capr entry
• convert inclusion rules to Capr attrition
• convert censor and end strategy to capr exit
• convert collapse strategy to capr era
• combine individual coersions to a capr cohort
• write and test readInCirce UI fn