Pass func_config to individual operator API

Updates the generate_api.py script and associated
templates to allow func_config and debug_config
to be passed when running individual operators
on the API.

This will allow us, for example, to set precise_mode
and abs_mode when running individual operators.

Signed-off-by: Grant Watson <grant.watson@arm.com>
Change-Id: Ia3e7ffc146f876daa307558433177c68285843b7