feat: request stop by skill name

[JarbasAl]

currently stop pipeline first checks active skill one by one to see if any wants to stop, if not then a global stop is sent

it should also be possible to request stopping a skill by name, not depending on the active order

"stop timer" "stop wikipedia"

this could be exposed to skills a few ways

class MySkill:
     def initiallize(self):
            self.register_stop_vocab("stop.voc")

with equivalent decorator

class MySkill:

     @stop_vocab("stop.voc")
     def stop(self):
            self.register_stop_vocab("stop.voc")

default name could be derived from the class, like OCP skills do

skill_name = camel_case_split(self.__class__.__name__)