Special:Contributions page allows searching for contributions from a range of ip addresses. The 2 User Contribution REST endpoints should follow suit and allow for range of contributions as well.

• /user/{user}/contributions
• /user/{user}/contributions/count

This can be done by adding 'cidr' to the array of allowed user types in the endpoint's param settings and adding the appropriate tests to UserContributionsHandlerTest, ContributionsCountHandlerTest, and the e2e Usercontributions.js test