* Add kernel caching mechanism to TileLang
- Implement a new `cached` function in `tilelang/cache/__init__.py` to cache and reuse compiled kernels
- Expose the `cached` function in the main `tilelang/__init__.py`
- Add a test case for cached matrix multiplication in `testing/python/cache/test_tilelang_cache_matmul.py`
- Provide a `clear_cache()` function to reset the kernel cache when needed
* Refactor kernel caching test and implementation
- Simplify the `cached` function in `tilelang/cache/__init__.py`
- Update test script `test_tilelang_cache_matmul.py` to use `tilelang.testing.main()`
- Remove unnecessary whitespace and improve code formatting
* Update import for `cached` function in MHA examples
- Modify import statement in `example_mha_bwd.py` and `test_tilelang_kernel_mha_bwd.py`
- Change import from `tilelang.profiler import cached` to `tilelang import cached`
- Align with recent refactoring of kernel caching mechanism
* Refactor `cached` function signature in kernel caching
- Update function signature to use keyword-only arguments for `target` and `target_host`
- Improve parameter order and readability of the `cached` decorator
- Maintain existing functionality while enhancing function definition
