[mlir][MemRef] Change the anchor point of a subview pattern

Essentially, this patches changes the anchor point of the
`extract_strided_metadata(subview)` pattern from
`extract_strided_metadata` to `subview`.

In details, this means that instead of replacing:
```
base, offset, sizes, strides = extract_strided_metadata(subview(src))
```
With
```
base, ... = extract_strided_metadata(src)
offset = <some math>
sizes = subSizes
strides = <some math>
```

We replace only the subview part and connect it back with a
reinterpret_cast:
```
val = subview(src)
```
=>
```
base, ... = extract_strided_metadata(src)
offset = <some math>
sizes = subSizes
strides = <some math>
val = reinterpret_cast base, offset, sizes, strides
```

Differential Revision: https://reviews.llvm.org/D135839