Rename 'draw' or 'drawcall' to action

* There's not a good accepted terminology for this kind of event, and for
  historical reasons 'drawcall' has been the accepted term, even though
  that can be quite confusing when a dispatch or a copy is a 'drawcall'.
* This is particularly highlighted by the event browser filters where
  $draw() includes draws and dispatches, but $dispatch() only includes
  dispatches, it's hard to intuitively understand why $draw() matches all
  of these calls.
* As a result we've defined the term 'action' to cover these types of
  events in the same way that we defined 'event' in the first place to
  mean a single atomic API call.

docs/python_api/renderdoc/analysis.rst

@@ -5,16 +5,16 @@ Replay Analysis
 
 .. currentmodule:: renderdoc
 
-Frame and Drawcalls
--------------------
+Frame and Actions
+-----------------
 
 .. autoclass:: FrameDescription
   :members:
 
-.. autoclass:: DrawcallDescription
+.. autoclass:: ActionDescription
   :members:
 
-.. autoclass:: DrawFlags
+.. autoclass:: ActionFlags
   :members:
 
 .. autoclass:: APIEvent