Add basic support for declarative Linalg transformations

Linalg ops provide a good anchor for pattern matching/rewriting transformations.
This CL adds a simple example of how multi-level tiling may be specified by attaching a simple StringAttr to ops as they are transformed so we can easily specify partial lowering to control transformation application.

This is a first stab at taking advantage of higher-level information contained in Linalg ops and will evolve in the future.

PiperOrigin-RevId: 277497958