[feature] add support for AltDiffusion/AltDiffusion-m9

[marscrazy]

We add support for AltDiffusion, which alters the text encoder of stable diffusion to extend the supported languages.

1. AltDiffusion uses the xlmr-large as the text encoder and supports both English and Chinese.
2. AltDiffusion-m9 also uses the xlmr-large as the text encoder and supports English(En), Chinese(Zh), Spanish(Es), French(Fr), Russian(Ru), Japanese(Ja), Korean(Ko), Arabic(Ar) and Italian(It).

References:

• AltDiffusion: https://huggingface.co/BAAI/AltDiffusion
• AltDiffusion-m9: https://huggingface.co/BAAI/AltDiffusion-m9
• paper:https://arxiv.org/abs/2211.06679

[marscrazy]

This PR also fix ISSUE #495

[patrickvonplaten]

You can also quite easy use it with diffusers: https://huggingface.co/BAAI/AltDiffusion-m9