Report HMR latency as trace spans for Turbopack (#60799)
This:
- Makes makes reporting hmr changes more accurate by emitting an
explicit start event and lowering the aggregation period for reporting
completed turbo tasks
- Parameterizes the aggregation period, allowing JS subscribers to
request different intervals, such as for the next-rs-api test
- Aligns path pattern with webpack by normalizing its layer names
- Fixes a bug in `drainAndGetNext` where the stream never could drain
past the first item
- Sends `client-hmr-latency` spans from Turbopack in both page and app
router pages
Closes PACK-2252
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Co-authored-by: Tobias Koppers <tobias.koppers@googlemail.com>
