Kernel::resume_thread was restricted to core when the targeted thread was in
another domain. Now there are two kernel calls, resume_local_thread and
resume_thread, where the former is never restricted and is provided via
public kernel/interface.h and the latter is always restricted to core and
is provided via core-local kernel/core_interface.h.
ref #1101
Kernel::pause_current_thread can be implemented much simpler and is not
restricted to core threads, in contrast to Kernel::pause_thread which
also benefits from the split and can be moved to core_interface.h.
ref #1101