[mlir][Linalg] Add basic support for TileAndFuse on Linalg on tensors.

This revision allows the fusion of the producer of input tensors in the consumer under a tiling transformation (which produces subtensors).
Many pieces are still missing (e.g. support init_tensors, better refactor LinalgStructuredOp interface support, try to merge implementations and reuse code) but this still allows getting started.

The greedy pass itself is just for testing purposes and will be extracted in a separate test pass.

Differential revision: https://reviews.llvm.org/D89491