Make log filename setting secure (see #11154).

This PR adds a UUID token server-side which is then compared in the ``CallContext`` invocation interceptor. This should stop anyone who isn't authenticated with the server be able to override the ``omero.logfilename`` setting and force the server to write outside the binary repository.

To test - verify that ``test_reporawfilestore.py`` doesn't fail.
--no-rebase as this is ``develop``-specific.