[VS/DPB] Introducing port_breakout_config_db.json

[vasant17]

Introducing port_breakout_config_db.json, which will be used when you…breakout port with -l option

Signed-off-by: Vasant [email protected]

- Why I did it
To provide default config for new created ports as part of breakout
- How I did it
port_breakout_config_db.json will have configuration of ports that will be loaded on creating a port as part of dynamic port breakout. To make use of this feature you have run the breakout CLI command with -l option.
Example: SONiC$ config interface breakout Ethernet0 4x25G[10G] -l -y

In the above example, Ethernet0 will be deleted and Ethernet0, Ethernet1, Ethernet2, and Ethernet3 will be craeted. If there is any configuration related these four ports is present in port_breakout_config_db.json, it'll be automatically configured. For example, adding port to VLAN, ACL or configuring an interface IP.

The file that we are checking in here is the one required for DPB VS test cases to exercise/test -l option.
- How to verify it
By running VS test cases
- Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)