[TRTLLM-4501] fit: AutoTuner tuning config refactor and add tuning for kernel configs.

The motivation for this PR is #4872, in which AutoTuner is applied to FP8 batched GEMM op with tile_size and epilog_tile_m to be in the argument list.
* Encoding different configs into a list of numeric tactic IDs starting from 0. This will be implemented inside kernels and used through get_valid_tactics.
* Define each config separately and let AutoTuner iterate over the combinations. This is more readable and flexible. Users can use each part of the config directly. There is no encoding-decoding process.

Add a config entry in the tuning config to define the valid candidates for each part of the config.
* AutoTuner will loop over a search grid generated from the config combinations.
* Each config will be tuned along with the specific input profile.
* The best config will be recorded in the cache value (instead of the cache key). And it will be recovered and used in the tunable runner forward.

Other enhancement:
* Use the decorator to make the tuning config definition more natural and efficient. This is an independent enhancement.
* Allow the user to not speficy the gen_tuning_buckets or the map_to_tuning_buckets function.
* Code refactoring.

Signed-off-by: Yukun He <[email protected]>

Author: hyukn