[mlir][affine] addLowerOrUpperBound: Make map+operand composing optional

There are cases in which it is not desirable to fully compose the bound map with the operands when adding lower/upper bounds to a `FlatAffineConstraints`.

E.g., this is the case when bounds should be expressed in terms of the operands only (and not the operands' dependencies). This also makes `addLowerOrUpperBound` useable together with operands that are defined through semi-affine expressions.

Differential Revision: https://reviews.llvm.org/D107221