Dbus service to support telemetry jwt operation

[saravanan-i]

Why I did it

Added Dbus handler to retrieve user roles for enabling telemetry dialin client to generate jwt token

How I did it

Retrieved user roles for an user from OS

How to verify it

1. Load Telemetry table (with client authentication mode as cert,password,jwt) using config load
2. Restart the telemetry docker
3. Request a new JWT token for admin user using gnoi_client
4. Observe that telemetry server returns the JWT token with expiry date

Which release branch to backport (provide reason below if selected)

• 202305

Description for the changelog

Dbus service to return user roles for an valid user present in sonic

Dependent Merge Requests:
sonic-net/sonic-buildimage#13142
sonic-net/sonic-gnmi#152