python-modules: add register_jinja_config_generator convenience fn

[alltilla]

Example usage:

python {
import syslogng

syslogng.register_jinja_config_generator(context="destination", name="my_dest", template=r"""

file({{ args.path }});

""")
};

destination d_my_dest{
  my-dest(path("/dev/stdout"));
};

TODO: make it possible to load .jinja file.

Signed-off-by: Attila Szakacs attila.szakacs@axoflow.com

[bazsi]

I think this should raise an exception if called as jinja2 might be unavailable if the user is not using a virtualenv.