Nornir-salt

BUG

1. Changed FC, FB, FX, FR filters pydantic models to non strict str type, so that can give any value such as number or boolean, as they are converted to strings anyway by FFun

9. Added dependency extras - netmiko, napalm, scrapli, pyats, netconf, gnmi, restconf, dataprocessor - to simplify installation using `pip install nornir-salt[xyz]`