MDM operation to return total number of Possible Duplicates

[jdar8]

Describe the issue
Knowing the total number of possible duplicates would give insights into the state of records and helps manage the workflow.
Customers have teams dedicated to manually resolving duplicates and having this value will help them estimate the work and how many records require manual review.
It also helps with troubleshooting and healthcheck. This is a trust exercise and it shows how well their MDM rule is doing.

Environment (please complete the following information):

• HAPI FHIR Version
• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]

Additional context
Add any other context about the problem here.