feat: Expose error classifier

[bbernays]

This PR exposes a way for plugins to capture and classify errors at a plugin level rather than having to handle it on a per resolver basis.

For example this can be utilized in our AWS plugin to handle 404s or AWS specific errors without having to replace or wrap the error handling in every single table resolver

Example PR that uses this functionality: https://github.com/cloudquery/cloudquery-private/pull/13197

[murarustefaan]

I think this is good overall, but requesting a review from @erezrokah as well before merging.

[Copilot]

Pull request overview

This PR introduces a plugin-configurable error classification hook so resolver errors can be suppressed at the scheduler/plugin level (e.g., ignoring expected 404s) rather than handled in each resolver.

Changes:

• Added schema.ErrorClassifier (+ supporting ErrorEvent/ErrorPhase) and threaded it through scheduler/resolver execution paths.
• Introduced scheduler.WithErrorClassifier(...) and wired the classifier into DFS + shuffle-queue worker execution and resource-chunk resolution.
• Added tests verifying default behavior (raised) vs suppressed behavior across strategies and resolver phases.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
schema/error_classifier.go	Adds the new public error-classifier API types and nil-safe helper.
scheduler/scheduler.go	Re-exports schema classifier types/phases and adds WithErrorClassifier.
scheduler/scheduler_shuffle_queue.go	Passes classifier into the shuffle-queue scheduler.
scheduler/scheduler_dfs.go	Consults classifier for table-resolver errors and passes it into chunk resolution.
scheduler/resolvers/resolvers.go	Adds classifier plumbing for chunk/column/pre/post resolver error handling.
scheduler/queue/scheduler.go	Adds option + field to carry classifier into queue workers.
scheduler/queue/worker.go	Consults classifier for table-resolver errors and passes it into chunk resolution.
scheduler/scheduler_error_classifier_test.go	Verifies scheduler-level suppression vs default SyncError emission across strategies.
scheduler/resolvers/resolvers_test.go	Updates existing resolver tests for new function signature.
scheduler/resolvers/error_classifier_test.go	Adds phase coverage tests ensuring suppression affects metrics and event metadata.

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