Rework S60DeviceRunconfiguration/RunControl.

- Prepare usage of 'make sis' target for GnuPoc.
- Change the package names to '_unsigned.sis', '.sis'
  instead of using '.sisx' for signed, adding accessors
  to S60DeviceRunconfiguration.
- Determine the local executable file name from the
  package template for GnuPoc (as it is no longer
  located under the SDK tree).