Extend loop unrolling and unroll-jamming to non-matching bound operands and

multi-result upper bounds, complete TODOs, fix/improve test cases.

- complete TODOs for loop unroll/unroll-and-jam. Something as simple as
  "for %i = 0 to %N" wasn't being unrolled earlier (unless it had been written
  as "for %i = ()[s0] -> (0)()[%N] to %N"; addressed now.

- update/replace getTripCountExpr with buildTripCountMapAndOperands; makes it
  more powerful as it composes inputs into it

- getCleanupLowerBound and getUnrolledLoopUpperBound actually needed the same
  code; refactor and remove one.

- reorganize test cases, write previous ones better; most of these changes are
  "label replacements".

- fix wrongly labeled test cases in unroll-jam.mlir

PiperOrigin-RevId: 238014653