Merge-contacts action should support mode where primary contacts are also merged

[kennsippell]

What feature do you want to improve?
The --merge-contacts action

Describe the improvement you'd like
If you merge two areas using merge-contacts, the result has two primary contacts. So for example, in eCHIS Kenya if I merge two CHP Areas the end result will be a single CHP Area but it will have two CHP contacts in it. This causes data integrity problems, dashboard problems, etc.

Add an optional flag like --merge-primary-contacts to the merge-contacts command which merges the primary contacts and their reports.

Describe alternatives you've considered
None

Additional context
None