gh-117142: ctypes: Unify meta tp slot functions (GH-117143)

Integrates the following ctypes meta tp slot functions:
* `CDataType_traverse()` into `CType_Type_traverse()`.
* `CDataType_clear()` into `CType_Type_clear()`.
* `CDataType_dealloc()` into `CType_Type_dealloc()`.
* `CDataType_repeat()` into `CType_Type_repeat()`.