A few improvements:
- Users can now specify types in a format like `UInt(4)`.
- Type representations are now more consistent with the new input
specification.
- Structs can be defined by extending the `Struct` class:
 https://github.com/llvm/circt/pull/4607
- Breaking change: module rename. `pycde.pycde_types` -> `pycde.types`.
- Compare and perform arithmetic on integer/bit signals and python ints.