vector.transfer operations do not have rank-reducing semantics.
Bail on illegal rank-reduction: we need to check that the rank-reduced
dims are exactly the leading dims. I.e. the following is illegal:
```
%0 = vector.transfer_write %v, %t[0,0], %cst :
vector<2x4xf32>, tensor<2x4xf32>
%1 = tensor.insert_slice %0 into %tt[0,0,0][2,1,4][1,1,1] :
tensor<2x4xf32> into tensor<2x1x4xf32>
```
Cannot fold into:
```
%0 = vector.transfer_write %v, %t[0,0,0], %cst :
vector<2x4xf32>, tensor<2x1x4xf32>
```
For this, check the trailing `vectorRank` dims of the insert_slice result
tensor match the trailing dims of the inferred result tensor.
Differential Revision: https://reviews.llvm.org/D116409
2e69f4f012