[trace] [intel pt] Create a "thread trace dump stats" command

When the user types that command 'thread trace dump info' and there's a running Trace session in LLDB, a raw trace in bytes should be printed; the command 'thread trace dump info all' should print the info for all the threads.

Original Author: hanbingwang

Reviewed By: clayborg, wallace

Differential Revision: https://reviews.llvm.org/D105717