affine.load/store: check for the right number of operands

Affine load and store operations take a variadic number of arguments, most of
which are interpreted as subscripts for the multi-dimensional memref they
access.  Add a verifier check that ensures the number of operands is equal to
the number affine remapping inputs if present and to the rank of the acessed
memref otherwise.  Although it is impossible to obtain such operations by
parsing the custom syntax, it is possible to construct them using the generic
syntax or programmatically.

PiperOrigin-RevId: 257605902