Turbopack: Add --internal-trace cli flag (#92190)
## What?
Adds `--internal-trace` to both `dev` and `build` that enables
`NEXT_TURBOPACK_TRACING=turbo-tasks`.
Optionally supports `minimal` and `all` (all is the default).
When `minimal` is provided it passes `NEXT_TURBOPACK_TRACING=1` and the
trace file won't include turbo-tasks spans.
