use crate_info.owner for linker inputs, if available (#4177)

Fixes an inconsistency where we use crate_info.owner as the owner of
Rust actions, while we used ctx.label as the owner of the corresponding
C++ linker inputs. Most of the time, these are the same, but we've got a
use case in rust proto integration where we wanna be able to customize
the owner of the C++ infos (so that these can be distinguished from the
C++ infos of the standard c++ proto bindings).