Also teach sunet-l4lb-namespace to load the nft ruleset if it exists.
While here modify the script so instead of running "once per netns
config file" we merge the interface config from each json file into the
same dict per namespace. Without this we would attempt to load the nft
ruleset twice (once per file that mentioned the namespace) or warn twice
if the file did not exist etc.
Patrik Lundin
39e1db9c32
