phosphor-ldap-conf: handle "PropertiesChanged" signal on the ldap cert object

 When LDAP client certificate is changed through Replace method on the cert object.
 Object would emit the signal "PropertiesChanged". Upon receiving the
 signal, config file would be updated with below given info if
 secure ldap is enabled:
         tls_cert <path client certificate file>
         tls_key  <path to client certificate file>

Tested By: Unit Tested

Signed-off-by: Ratan Gupta <ratagupt@linux.vnet.ibm.com>
Change-Id: I5347b13e0bf76742d39dc7a26c96ec5d4dd5a2c6
3 files changed