Reuse existing import if already defined in the file

[RIP21]

If we move from let say packlets/utils to @acme/utils and in the file, there is already a @acme/utils imports we should add imports to it and do not create a new one.

So from:

import { fn1 } from 'packlets/utils'
import { fn2 } from '@acme/utils'

To:

import { fn2, fn1 } from '@acme/utils'

Currently it will generate following:

import { fn1 } from '@acme/utils'
import { fn2 } from '@acme/utils'