T6335: Add/Update EVPN op commands

Converted completion helpers from python to bash for performance

Previous commit:
Added the following commands:
show evpn
show evpn es
show evpn es <es-id>
show evpn es detail
show evpn es-evi
show evpn es-evi detail
show evpn es-evi vni <num>
show evpn vni
show evpn vni detail
show evpn vni <num>

Updated the following commands:
show evpn access-vlan
show evpn arp-cache
show evpn mac
show evpn next-hops
show evpn rmac

(cherry picked from commit 3917e3e9f985063ab7419c903f6019116224f640)