T6486: T6379: Rewrite generate openvpn client-config (#3926)

This command helps to generate users .ovpn files
Rewrite generate openvpn client-config to use Config()
It needs to get the default values as ConfigTreeQuery is
not supporting default values.

Fixed "ignores configured protocol type" if TCP is used
Fixed lzo, was used even if lzo not configured
Fixed encryption is not parse the dict

(cherry picked from commit fe50f1a9292b34e168b35453f2cfc2aee2ca4843)

Co-authored-by: Viacheslav Hletenko <v.gletenko@vyos.io>