[TACACS] Encrypt TACACS secret key with predefined shared key.

[shihhsien-wang]

What I did

What I did:

To encrypt the TACACS secret key using a predefined shared key.

How I did it

To encrypt the key with predefined shared key before placing it in the configuration and decrypt it before use, for enhanced security.

sonic-host-services also modified for the requirement: https://github.com/sonic-net/sonic-host-services/pull/127

How to verify it

To configure secret key using a CLI command and verified that the secret key could be used (e.g., for authentication) and that the encrypted string was visible in the configuration.

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)