[lldb/API] Introduce SBProcess::ForceScriptedState method

This patch introduces a new method to the SBProcess API called
ForceScriptedState. As the name suggests, this affordance will allow the
user to alter the state of the scripted process programatically.

This is necessary to update the scripted process state when perform
interactive debugging.

Differential Revision: https://reviews.llvm.org/D145294



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