[ENG-381] feat: add extension support for datapoints (#3661)

* feat: add extension support for datapoints

* refact:updated the extension mapping

* chore: switch to just json

---------

Co-authored-by: nandkishorr <rachulr7@gmail.com>

Author: Jacobjeevan

care/emr/reports/context_builder/data_points/patient.py

@@ -169,6 +169,16 @@ class BasePatientContextBuilder(SingleObjectContextBuilder):
         preview_value="",
         description="Instance tags associated with the patient",
     )
+    extensions = Field(
+        display="Patient Extensions",
+        mapping=lambda p: p.extensions or {},
+        preview_value={
+            "patient_demographics": {
+                "related_person": "Jane Doe",
+            },
+        },
+        description="Patient extensions as JSON (e.g. patient.extensions.patient_demographics)",
+    )
 
 
 class PatientMinimumContextBuilder(BasePatientContextBuilder):