The namespace can be specified using the `cppNamespace` field. This matches the functionality already present on dialects, enums, etc. This fixes problems with using interfaces on operations in a different namespace than the interface was defined in.
Differential Revision: https://reviews.llvm.org/D83604
This revision adds support to ODS for generating interfaces for attributes and types, in addition to operations. These interfaces can be specified using `AttrInterface` and `TypeInterface` in place of `OpInterface`. All of the features of `OpInterface` are supported except for the `verify` method, which does not have a matching representation in the Attribute/Type world. Generating these interface can be done using `gen-(attr|type)-interface-(defs|decls|docs)`.
Differential Revision: https://reviews.llvm.org/D81884