Added missing handler for executable path retrieval message

Added missing handler for executable path retrieval message

[Issue#] SSDWSSP-274
[Feature/Bug] N/A
[Problem] SECURITY_SERVER_MSG_TYPE_EXE_PATH_REQUEST is not handled
[Cause] Incorrectly resolved conflict. Part of code lost.
[Solution] Missing handler restored

[Verification] Build & install. Run security-server-tests-client-smack
--regexp=tc06_check_privilege_by_sockfd. Security server logs should contain
valid executable path in lines starting with SS_SMACK. There should be no
"Unknown msg ID" message in dlog

Change-Id: I8e384e645291a0563a1ffd4ce47496742e756742