[`attn_implementation`] remove recursive, allows custom kernels with wrappers (#39823)
* fix?
* fixme and style
* Update src/transformers/modeling_utils.py
* update
* update
* fix
* small fixees
* nit
* nits
* fix init check?
* fix
* fix default
* or fucks me
* nits
* include a small nit
* does this make it hapy?
* fixup
* fix the remaining ones