Replication issue diagnostics

[rkistner]

This uses the persisted timestamp for last commit/keepalive to report replication issues in the diagnostics API.

If the replication stream is idle, a new keepalive should be performed once every minute. This means we cannot test more granular than that, but this should report cases where:

1. The replication process is down completely.
2. The replication process is active, but does not perform any new commits. One example of such a case is in [MongoDB] Fix resume token handling when no events are received #251.

However, this will not detect cases where the replication process makes progress but falls behind. For those cases, monitor the powersync_replication_lag_seconds metric instead.

This change also reduces the Postgres keepalive message interval from 5 minutes to 1 minute. We already have a different keepalive mechanism in MongoDB doing the same.

TODO:

• Check keepalives for MySQL replication.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0c224d0

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

This PR includes changesets to release 11 packages

Name	Type
@powersync/service-core	Minor
@powersync/service-image	Minor
@powersync/service-core-tests	Patch
@powersync/service-module-core	Patch
@powersync/service-module-mongodb-storage	Patch
@powersync/service-module-mongodb	Patch
@powersync/service-module-mysql	Patch
@powersync/service-module-postgres-storage	Patch
@powersync/service-module-postgres	Patch
test-client	Patch
@powersync/service-schema	Minor

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