config portchannel add/del <portchannel_name> - check for member being part of some other portchannel

[kannankvs]

This command is used to add or delete the portchannel.
When any port is already a member of any other portchannel and if user tries to add the same port in some other portchannel (without deleting it from the current portchannel), the command fails internally. But, it does not print any error message. In such cases, user is expected to remove the member from current portchannel and then add it to new portchannel.
Improve this implementation to return failure for this command if user tries to add a port to a portchannel but if the same port is already made member of some other portchannel.
It is better to print "Port is already member of PortChannelxxx, Remove it from PortChannelxxxx before adding it to this PortChannelyyyy".

[AkhileshSamineni]

You can close this issue, I have fixed this issue using PR - sonic-net/sonic-utilities#1328