Fixup TestPyObjSynthProvider.py and enable it again

Summary:
- copies the new file in the cmake build
- adds an additional import statement
- marks the test as no-debug-info specific, as it seems to be testing a python feature

Reviewers: granata.enrico

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D24074

llvm-svn: 280261