feat(attributes): Add db.stored_procedure.name and ensure span name attribute consistency

[Lms24]

I noticed that the db.stored_procedure.name attribute mentioned in the db span name template wasn't documented in conventions yet. This PR adds the attribute and a test that ensures that any attribute mentioned in span name templates exists as an attribute in conventions.

[github-actions]

Semver Impact of This PR

🟡 Minor (new features)

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New Features ✨

• (attributes) Add db.stored_procedure.name and ensure span name attribute consistency by Lms24 in #398

• (schema) Add additional_context field to attribute definitions by matejminar in #393

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