Log user_id and sync stats for each connection

[rkistner]

This additionally adds some additional fields to structured logs, for easier processing if desired.

Sample log output for a single HTTP request:

info: New checkpoint: 2686394 | write: null | buckets: 2 ["global[]","by_user[\"test\"]"] {"buckets":2,"checkpoint":"2686394","user_id":"test"}
info: Sync stream complete {"data_synced_bytes":14291587,"operations_synced":2402,"user_id":"test"}
info: POST /sync/stream {"duration_ms":181,"method":"POST","path":"/sync/stream","route":"/sync/stream","status":200}

JSON log format:

{"buckets":2,"checkpoint":"2686394","level":"info","message":"New checkpoint: 2686394 | write: null | buckets: 2 [\"global[]\",\"by_user[\\\"test\\\"]\"]","timestamp":"2024-07-17T09:05:33.532Z","user_id":"test"}
{"data_synced_bytes":14291587,"level":"info","message":"Sync stream complete","operations_synced":2402,"timestamp":"2024-07-17T09:05:33.780Z","user_id":"test"}
{"duration_ms":252,"level":"info","message":"POST /sync/stream","method":"POST","path":"/sync/stream","route":"/sync/stream","status":200,"timestamp":"2024-07-17T09:05:33.780Z"}

[changeset-bot]

🦋 Changeset detected

Latest commit: bdbf95c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@powersync/service-core	Patch
@powersync/service-image	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[stevensJourney]

Awesome