[mlir] Add support for defining Traits and Interfaces on Attributes/Types.

[mlir] Add support for defining Traits and Interfaces on Attributes/Types.

This revisions add mechanisms to Attribute/Type for attaching traits and interfaces. The mechanisms are modeled 1-1 after those for operations to keep the system consistent. AttrBase and TypeBase now accepts a trailing list of `Trait` types that will be attached to the object. These traits should inherit from AttributeTrait::TraitBase and TypeTrait::TraitBase respectively as necessary. A followup commit will refactor the interface gen mechanisms in ODS to support Attribute/Type interface generation and add tests for the mechanisms.

Differential Revision: https://reviews.llvm.org/D81883