Mgmt-unsolicited feature CLI

[lfridlander]

What I did

Add CLI for 'mgmt-unsolicited' feature according to HLD

How I did it

Added CLI commands to:

• Configure 'mgmt-unsolicited' feature state
• Related show command

How to verify it

Manual testing

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)