We started to call Authority argument $performer everywhere,
and $performer->getPerformer() doesn't look that good.
Change-Id: Id2cf3f27b18340314e4ed1ea9931ad9404b4df6f
Rename path param "name" to user in UserContributions endpoints.
Name is more appropriate as "name" could be username as
well as IP address or range of IP addresses.
It also fits better with the implementation, as the
user parameter gets validated as a User object.
Bug: T259680
Change-Id: I6a146d99d1063c250f2ac460e4576bc287259766
