Implemented MIOpenDriver support for different output type

[DrizztDoUrden]

This adds MIOpenDriver conv* argument --output_type/-M, that supports values same and fp32 and thus allows launching convolution with float output data type despite input and weights types being different. ConvArgsForMIOpenDriver (MIOPEN_ENABLE_LOGGING_CMD=1) now also adds this option when applicable. Without the changes some printed commands were not executable due to some solvers requiring float output for int8 input.