[MLIR][Shape] Remove deprecated and unused lowerings

This concerns `from/to_extent_tensor`, `size_to_index`, `index_to_size`, and
`const_size` conversion patterns. The new lowering will work directly on indices
and extent tensors. The shape and size values will allow for error values but
are not yet supported by the dialect conversion.

Differential Revision: https://reviews.llvm.org/D84436