UnaryOperation/BinaryOperation do not have type information as expected

### Describe the desired feature

UnaryOperation/BinaryOperation are subclasses of ExpressionTyped class, however their "type" property records their "operation type" (such as `BANG`, `TILD`, `DELETE`), not Solidity types (like `int` or `uint`). I think this is counter-intuitive and certainly not consistent with other subclasses of ExpressionTyped like `AssignmentOperation`, `Identifier`, etc.

Unary/Binary operation classes should record `expression["typeDescriptions"]["typeString"]` in the `type` property and have a separate property (say, "operation") for the type of operation.