unit/test-gatt: Add /TP/GAW/CL/BV-02-C/seclevel test
unit/test-gatt: Add /TP/GAW/CL/BV-02-C/seclevel test

This add a test for signed write but with security level other than low
so we can verify the code use the write instead of signed write.

ComputeCycles/bluez,pkarasev3/bluez,mapfau/bluez,pkarasev3/bluez,silent-snowman/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,mapfau/bluez,silent-snowman/bluez,silent-snowman/bluez,mapfau/bluez,silent-snowman/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez