[mlir][linalg] Swap tensor.extract_slice(linalg.fill)

This commit adds a pattern to swap

```
tensor.extract_slice(linalg.fill(%cst, %init))
```
into
```
linalg.fill(%cst, tensor.extract_slice(%init))
```
when the linalg.fill op have no other users.
This helps to reduce the fill footprint.

Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D134102