Added buffer wait operations and some refactoring

Added methods to use buffer wait operations.
Created classes for each kind of bus operation: ReadOperation,
WriteOperation, TimeoutOperation, DelayOperation, BufferWaitOperation.

api/scaffold/__init__.py

@@ -1999,14 +1999,17 @@ def timeout_section(self, timeout):
         """
         return self.bus.timeout_section(timeout)
 
+    def buffer_wait_section(self):
+        return self.bus.buffer_wait_section()
+
     def delay(self, duration: float):
         """
         Performs a delay operation.
 
         :param cycles: Delay duration in seconds.
         """
         cycles = round(duration * self.sys_freq)
-        self.bus.operation_delay(cycles)
+        self.bus.delay(cycles)
 
 
 class Scaffold(ArchBase):