fix: multivariable declaration parsing error

[jaw52]

Regular expression parsing fails when multiple variables are declared in a single line in JavaScript

for example

const a = 1, ref = 2

Afterunimport processing, resulting in repeated import

+ import {ref} from 'vue'
const a = 1, ref = 2

close #223

[antfu]

As RegExp is not turning complete, it's not possible to handle all the cases. This PR introduces other regressions nuxt/nuxt#21807 that I see are more commonly used. We need to make a trade-off here. I have reverted this change until we find better solutions, otherwise, I guess we would need to document what's the caveats are.