[mlir][Transforms] GreedyPatternRewriteDriver: Worklist randomizer

Instead of always taking the last op from the worklist, take a random one. For testing/debugging purposes only. This feature can be used to ensure that lowering pipelines work correctly regardless of the order in which ops are processed by the GreedyPatternRewriteDriver.

The randomizer can be enabled by setting a numeric `MLIR_GREEDY_REWRITE_RANDOMIZER_SEED` option.

Note: When enabled, 27 tests are currently failing. Partly because FileCheck tests are looking for exact IR.

Discussion: https://discourse.llvm.org/t/discussion-fuzzing-pattern-application/67911

Differential Revision: https://reviews.llvm.org/D142447