[lldb/crashlog] Add support for Application Specific Backtraces & Information

For an exception crashlog, the thread backtraces aren't usually very helpful
and instead, developpers look at the "Application Specific Backtrace" that
was generated by `objc_exception_throw`.

LLDB could already parse and symbolicate these Application Specific Backtraces
for regular textual-based crashlog, so this patch adds support to parse them
in JSON crashlogs, and materialize them a HistoryThread extending the
crashed ScriptedThread.

This patch also includes the Application Specific Information messages
as part of the process extended crash information log. To do so, the
ScriptedProcess Python interface has a new GetMetadata method that
returns an arbitrary dictionary with data related to the process.

rdar://93207586

Differential Revision: https://reviews.llvm.org/D126260

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

lldb/source/Plugins/Process/scripted/ScriptedProcess.cpp

@@ -485,6 +485,19 @@ ScriptedProcess::GetLoadedDynamicLibrariesInfos() {
   return loaded_images_sp;
 }
 
+lldb_private::StructuredData::DictionarySP ScriptedProcess::GetMetadata() {
+  CheckInterpreterAndScriptObject();
+
+  StructuredData::DictionarySP metadata_sp = GetInterface().GetMetadata();
+
+  Status error;
+  if (!metadata_sp || !metadata_sp->GetSize())
+    return ScriptedInterface::ErrorWithMessage<StructuredData::DictionarySP>(
+        LLVM_PRETTY_FUNCTION, "No metadata.", error);
+
+  return metadata_sp;
+}
+
 ScriptedProcessInterface &ScriptedProcess::GetInterface() const {
   return m_interpreter->GetScriptedProcessInterface();
 }