WebGPURenderer: OperatorNode Add unary operator support

[RenaudRohlinger]

Adds bitNot and not support to OperatorNode. For these type of operator the second node doesn't exist so I handled that too. For example:

const a = b.bitNot(); // no second operator
c.assign( a.bitAnd( a ) );
d.assign( d.not() ); // no second operator

This contribution is funded by Utsubo