[lldb/Plugins] Add support for ScriptedThread in ScriptedProcess

This patch introduces the `ScriptedThread` class with its python
interface.

When used with `ScriptedProcess`, `ScriptedThreaad` can provide various
information such as the thread state, stop reason or even its register
context.

This can be used to reconstruct the program stack frames using lldb's unwinder.

rdar://74503836

Differential Revision: https://reviews.llvm.org/D107585

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedPythonInterface.cpp

@@ -35,6 +35,14 @@ ScriptedPythonInterface::GetStatusFromMethod(llvm::StringRef method_name) {
   return error;
 }
 
+template <>
+StructuredData::DictionarySP
+ScriptedPythonInterface::ExtractValueFromPythonObject<
+    StructuredData::DictionarySP>(python::PythonObject &p, Status &error) {
+  python::PythonDictionary result_dict(python::PyRefType::Borrowed, p.get());
+  return result_dict.CreateStructuredDictionary();
+}
+
 template <>
 Status ScriptedPythonInterface::ExtractValueFromPythonObject<Status>(
     python::PythonObject &p, Status &error) {