[mlir][MemRef] Simplify extract_strided_metadata(expand_shape)
Add a pattern to the pass that simplifies
extract_strided_metadata(other_op(memref)).
The new pattern gets rid of the expand_shape operation while
materializing its effects on the sizes, and the strides of
the base object.
In other words, this simplification replaces:
```
baseBuffer, offset, sizes, strides =
extract_strided_metadata(expand_shape(memref))
```
With
```
baseBuffer, offset, baseSizes, baseStrides =
extract_strided_metadata(memref)
sizes#reassIdx =
baseSizes#reassDim / product(expandShapeSizes#j,
for j in group excluding
reassIdx)
strides#reassIdx =
baseStrides#reassDim * product(expandShapeSizes#j,
for j in
reassIdx+1..
reassIdx+group.size-1)
```
Where `reassIdx` is a reassociation index for the group at
`reassDim` and `expandShapeSizes#j` is either:
- The constant size at dimension j, derived directly from the
result type of the expand_shape op, or
- An affine expression: baseSizes#reassDim / product of all
constant sizes in expandShapeSizes.
Note: baseBuffer and offset are unaffected by the expand_shape
operation.
Differential Revision: https://reviews.llvm.org/D133625