[WIP] Added scheduler

src/cpl_reactive_extensions/abc/scheduler_action.py

@@ -0,0 +1,10 @@
+from abc import ABC, abstractmethod
+
+from cpl_core.type import T, Number
+from cpl_reactive_extensions.internal.subscription import Subscription
+
+
+class SchedulerAction(ABC):
+    @abstractmethod
+    def schedule(self, state: T = None, delay: Number = None) -> Subscription:
+        pass