Add more compliance tests for the extras

[VisLab]

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[Copilot]

Pull request overview

Adds new schema-compliance checks around “extras” completeness and annotation attribute validity, and updates/extends the test suite to account for warnings vs. errors in compliance output.

Changes:

• Add two new compliance checks: extras_columns and annotation_attributes (both treated as warnings).
• Expand schema compliance tests to validate these new checks and adjust expectations for known base-schema annotation warnings.
• Update spec tests and schema validation tooling to filter compliance results by ErrorSeverity.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
tests/schema/test_schema_format_roundtrip.py	Adjusts compliance assertion to only fail on ERROR-severity issues.
tests/schema/test_schema_compliance.py	Updates summary expectations and adds test coverage for new extras/annotation compliance checks.
spec_tests/test_errors.py	Filters out WARNING compliance issues of a specific code during schema spec tests.
spec_tests/hed-tests	Bumps hed-tests submodule revision.
hed/scripts/schema_script_util.py	Treats only ERROR-severity compliance issues as validation failures.
hed/schema/schema_validation/compliance.py	Implements check_extras_columns and check_annotation_attribute_values; modifies severity handling.
hed/errors/schema_error_messages.py	Adds new schema error messages for extras/annotation compliance warnings.
hed/errors/error_types.py	Adds new SchemaAttributeErrors constants for extras and annotation checks.
.github/workflows/links.yaml	Updates lychee link checker GitHub Action version.

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