Add input validation on installer to avoid iPSK database user and ISE ODBC user to be the same (leads to "Creation of Cisco ISE MySQL user failed")

[AnthoBalitrand]

Issue

On installer, if "iPSK database username" and "Cisco ISE ODBC Username" have the same values, the install script indeed tries to create 2 mySQL users with the same username, which leads to the "Creation of Cisco ISE MySQL user failed" error. (On backend, mySQL error 1396).

Suggested solution

Add data validation on the installer form to avoid those 2 values to be the same.