[lldb/swig] Fix ref counting issue in SBProcess::GetScriptedImplementation

[lldb/swig] Fix ref counting issue in SBProcess::GetScriptedImplementation

When using SBProcess::GetScriptedImplementation in python, if the
process has a valid implementation, we returned a reference of the
object without incrementing the reference counting. That causes the
interpreter to crash after accessing the reference several times.

This patch address this by incrementing the reference count when passing
the valid object reference.

Differential Revision: https://reviews.llvm.org/D145260

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