Add initial support to the SourceMgrDiagnosticHandler for printing call stacks.

    Example:

    /tmp/file_C.py:17:1: error: 'foo.bar' op attribute 'something' ...
      app.run(main)
    ^
    /tmp/file_D.py:14:1: note: called from
        raise app.UsageError('Too many command-line arguments.')
    ^
    /tmp/file_E.py:12:1: note: called from
    def main(argv):
    ^
    /tmp/file_F.py:13:1: note: called from
      if len(argv) > 1:
    ^

--

PiperOrigin-RevId: 248074804