[VLMs] support attention backends (#37576)
* update models
* why rename
* return attn weights when sdpa
* fixes
* fix attn implementation composite
* fix moshi
* add message
* add typings
* use explicitly all flags for each attn type
* fix some tests
* import what is needed
* kosmos on main has ew attention already, yay
* new models in main, run fixup
* won't fix kosmos yet
* fix-copies
* clean up after rebasing
* fix tests
* style
* dont cast attns to fp32
* did we update ruff? oke, let's just do what it asks
* fix pixtral after rebase
