Deprecate "cohort_multi_variable" and instead refactor "irae__cohort_study_variables_wide"

[comorbidity]

cohort_multi_variable creates a view from multiple FHIR Resources (Condition, Rx MedicationRequest, Observation, Procedure) into a single table/view for easier counting and exploratory analysis. For example, diabetes is a condition that is treated with medications and HA1C/glucose observations.

• cohort_multi_variable.sql
• multi_variables.py

This feature has been helpful in the past but might be redundant since the introduction of the WIDE study variables view.

[comorbidity]

The tables as they exist today are "valid", however, the structure makes it hard to to actually SQL Select and the resulting SQL counts can be misleading. What is needed is the collation column-wise at the level of encounter_ref and subject_ref such as seen here:

        casedef.subject_ref,
        arbitrary(dx_transplant)    FILTER (WHERE dx_transplant     IS NOT NULL) AS dx_transplant,
        arbitrary(dx_autoimmune)    FILTER (WHERE dx_autoimmune     IS NOT NULL) AS dx_autoimmune,
        arbitrary(dx_cancer)        FILTER (WHERE dx_cancer         IS NOT NULL) AS dx_cancer
from    irae__cohort_study_variables_wide   as wide , 
        irae__cohort_casedef                as casedef
where   wide.subject_ref = casedef.subject_ref        
GROUP BY casedef.subject_ref;