[mlir][tosa] Add shape inference for tosa.while

Tosa.while shape inference requires repeatedly running shape inference across
the body of the loop until the types become static as we do not know the number
of iterations required by the loop body. Once the least specific arguments are
known they are propagated to both regions.

To determine the final end type, the least restrictive types are determined
from all yields.

Differential Revision: https://reviews.llvm.org/D108801