activate: allow multiple, possibly invalid, fd names

activate: allow multiple, possibly invalid, fd names

Previous code only allowed a single name to be passed, and duplicated
it over all descriptors. For the sake of testing, allow different
names and in arbitrary number. If just one is given, duplicate it
to match the number of sockets. This matches previuos behaviour.

Since this is a testing tool, it seems useful to allow passing invalid
names to test application behaviour with invalid names. Hence, only
warn. When warning, escape the name.