Implement `named_import_transform` (#54530)
This is the first step to enable the automatic "modularize imports"
optimization for some libraries. It transforms named imports like
`import { A, B, C as F } from 'foo'` to a special loader string: `import
{ A, B, C as F } from "barrel-optimize-loader?names=A,B,C!foo"`.
In a follow-up PR we'll apply corresponding optimization with another
SWC transformer.
