[mlir][Vector] Add Broadcast -> CastOp reordering to SinkVectorBroadcasting patterns. (#68257)

Also fix an issue with sink broadcast across elementwise where
`arith.cmpf` is elementwise, but result type is different. The result
type is not same as the operand type, creating illegal IR.
Similar issue with `vector.fma` which only accepts vector operand types,
while broadcasts can have scalar sources. Sinking broadcast across would
result in an illegal `vector.fma` (with scalar operands).