Adding provider credentialing dates

Upcoming changes (Aug 4, 2023)

We plan on making the following changes to the Medallion public API (non-breaking):

Adding initial_credentialing_date, latest_credentialing_date to the GET Providers endpoint response

Scope: This affects the following endpoints:

• https://api.medallion.co/api/v1/org/providers/

Motivation: This will provide users visibility into relevant credentialing dates for providers that have credentialing.