Implement support for the SSH2_AGENTC_REMOVE_IDENTITY
agent protocol message.
The implementation mirrors ssh_agent_sign_data()
and reuses agent_talk(). A single cleanup path is
used to ensure proper resource handling.
Signed-off-by: Madhav Vasisth <mv2363@srmist.edu.in>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>