Revert "Revert "Add the ability to write target stop-hooks using the ScriptInterpreter.""

This reverts commit f775fe5964.

I fixed a return type error in the original patch that was causing a test failure.
Also added a REQUIRES: python to the shell test so we'll skip this for
people who build lldb w/o Python.
Also added another test for the error printing.

lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h

@@ -105,6 +105,14 @@ public:
   lldb::SearchDepth ScriptedBreakpointResolverSearchDepth(
       StructuredData::GenericSP implementor_sp) override;
 
+  StructuredData::GenericSP
+  CreateScriptedStopHook(lldb::TargetSP target_sp, const char *class_name,
+                         StructuredDataImpl *args_data, Status &error) override;
+
+  bool ScriptedStopHookHandleStop(StructuredData::GenericSP implementor_sp,
+                                  ExecutionContext &exc_ctx,
+                                  lldb::StreamSP stream_sp) override;
+
   StructuredData::GenericSP
   CreateFrameRecognizer(const char *class_name) override;