Introduce `next analyze`: a built-in bundle analyzer for Turbopack (#85915)
This implements `next experimental-analyze`, which generates bundle analyzer data without without writing chunks or other artifacts to disk. It also optionally serves the bundle analyzer so it can be browsed easily.
Examples:
`next experimental-analyze` - writes analyzer data and UI to `.next/diagnostics/analyze`
`next experimental-analyze --serve` - writes analyzer data and UI as well as serves the files on a static file server on localhost (by default on port 4000)
`next experimental-analyze --serve --port 4001` -- runs the above on port 4001