@hyf0

This change could be considered a major update that breaks https://github.com/unplugin/unplugin-isolated-decl

1. This plugin didn't treat Rolldown specially but regarded it as Rollup.
2. It relies on the default value of NormalizedOutputOptions.entryFileNames, which is [name].js in Rollup, but now it's undefined.
3. NormalizedInputOptions.input is string[] | Record<string, string> in Rollup and can be a string in Rolldown.

If this is by design, I hope the Rolldown team will reconsider.

Originally posted by @sxzz in #2835