Refactor FHIRCarePlanGenerator Class

[f-odhiambo]

This is a follow-up for https://github.com/opensrp/fhircore/pull/3385 to be worked on in the next CHT

• [ ] Remove hardcoded string variables such as the one in the below comment and accommodate all references as described in the spec https://hl7.org/fhir/R4B/careplan-definitions.html#CarePlan.instantiatesCanonical

Sample code

listOf(CanonicalType("PlanDefinition/$canonicalValue"))

[f-odhiambo]

Here is one

 // TODO refactor this code to remove hardcoded appended "PlanDefinition/" on https://github.com/opensrp/fhircore/issues/3386
  private fun CarePlan.cleanPlanDefinitionCanonical() {
    val canonicalValue = this.instantiatesCanonical.first().value
    if (canonicalValue.contains('/').not()) {
      this.instantiatesCanonical = listOf(CanonicalType("PlanDefinition/$canonicalValue"))
    }
  }