[request]: export `variantToStyle` util

[ijkml]

I understand the variantToStyle function might be a low-level util, but it would be awesome to expose it for those who [think they] know what they're doing :sweat_smile:, instead of copy-pasting.

https://github.com/vueuse/motion/blob/main/src/utils/transform.ts

Please let me know what you think.