[mlir][VectorOps] Add fold `ExtractOp(CreateMask) -> CreateMask` (#69456)

This allows folding extracts from `vector.create_mask` ops that have a
known value. Currently, there's no fold for this, but you get the same
effect from the unrolling in LowerVectorMask (part of
-convert-vector-to-llvm), then folds after that. However, for a future
patch, this simplification needs to be done before lowering to LLVM,
hence the need for this fold.

E.g.:

```
%0 = vector.create_mask %c1, %dimA, %dimB : vector<1x[4]x[4]xi1>
%1 = vector.extract %mask[0] : vector<[4]x[4]xi1>
```
->
```
%0 = vector.create_mask %dimA, %dimB : vector<[4]x[4]xi1>
```

0 files changed, 0 insertions, 0 deletions