CLI support for PAC

[vijaya-ops]

What I did

The cli changes are implemented as per the HLD mentioned below. https://github.com/sonic-net/SONiC/pull/1655

How I did it

Implemented the below commands

Config commands

config dot1x system-auth-control enable
config interface authentication port-control Ethernet0 auto
config interface authentication host-mode Ethernet0 multi-auth
config interface authentication order Ethernet0 dot1x
config interface authentication priority Ethernet0 dot1x
config interface dot1x pae Ethernet0 authenticator
config interface authentication periodic Ethernet1 enable
config interface authentication reauth-period Ethernet1 120
config interface authentication max-users Ethernet1 6
config interface mab Ethernet1 enable -a pap

=============== Show commands

show authentication interface show authentication clients show mab interface show dot1x

============ Clear commands

sonic-clear authentication sessions

How to verify it

[adyeung]

@jeff-yin @ridahanif96 pls help review

[vijaya-ops]

/azpw run Azure

[mssonicbld]

/AzurePipelines run Azure

[azure-pipelines[bot]]

No pipelines are associated with this pull request.