Add edsc::ops for pointwise, conv and dilated_conv

This CL adds more Linalg EDSC ops and tests to support building pointwise operations along with conv and dilated_conv.
This also fixes a bug in the existing linalg_matmul EDSC and beefs up the test.

The current set of ops is already enough to build an interesting, albeit simple, model used internally.

PiperOrigin-RevId: 285838012