Add KVAE 1.0

[ddavidchick]

What does this PR do?

Add KVAE1.0 from Kandinsky team. git repo.

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@yiyixuxu @asomoza

[yiyixuxu]

thanks for the PR!
Can you explain what is this used for/with? is it mainly for future research, or can we use it with an existing Kandinsky 5 pipeline we support?

[ddavidchick]

KVAEs are autoencoders with strong reconstruction quality and a well-structured latent space, developed by our team. They weren't used in Kandinsky 5, as they were created a bit later, so this is mainly for future research. They can be used as a VAE backbone for developing new diffusion models.