[TRTLLM-4501][feat] AutoTuner tuning config refactor and valid tactic generalization. (#6545)

* Generalize the definition of tactics so that users can implement more customizable tactic types, making the configurations clearer for each kernel run. 
* Allow the user not to specify the `gen_tuning_buckets` or the `map_to_tuning_buckets` function.
* Other code refactoring.

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

Author: hyukn