Mostly gemma2 support FA2 softcapping!

but also fix the sliding window for long context and other typos.

• [Gemma2] Support FA2 softcapping (#31887) by @ArthurZucker
• [ConvertSlow] make sure the order is preserved for addedtokens (#31902) by @ArthurZucker
• Fixes to alternating SWA layers in Gemma2 (#31775) by @turboderp
• Requires for torch.tensor before casting (#31755) by @echarlaix

Was off last week could not get this out, thanks all for your patience 🥳