[mlir][VectorOps] Extend vector.constant_mask to support 'all true' scalable dims (#66638)

This extends `vector.constant_mask` so that mask dim sizes that
correspond to a scalable dimension are treated as if they're implicitly
multiplied by vscale. Currently this is limited to mask dim sizes of 0
or the size of the dim/vscale. This allows constant masks to represent
all true and all false scalable masks (and some variations):

```
// All true scalable mask
%mask = vector.constant_mask [8] : vector<[8]xi1>

// All false scalable mask
%mask = vector.constant_mask [0] : vector<[8]xi1>

// First two scalable rows
%mask = vector.constant_mask [2,4] : vector<4x[4]xi1>
```