Add module for PheValuator

[anthonysena]

Let's add a module to evaluate phenotypes using PheValuator. Tagging @jswerdel for awareness.

[anthonysena]

Capturing some notes from the discussion on this topic:

• It may be possible to create the cohorts used as inputs when running PheValuator (i.e. xSpec, xSens, Prevalence) using some templates via CapR or CohortGenerator.
• When evaluating a phenotype (cohort) via PheValuator, it is important to know if it is an acute or chronic condition so that the appropriate cohort inputs & parameters are selected. There are some recommended defaults for chronic & acute conditions.