chore(images/ebnf): add scan.svg

Summary

• chore(images/ebnf): add scan.svg

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• Close nothing
• Cherry-pick to: 24.4 / 24.3
• Staging:
  • https://docs.binary.picodata.io/picodata/asabirov_update_ebnf_diagrams/reference/sql/select/#syntax
  • https://docs.binary.picodata.io/picodata/asabirov_update_ebnf_diagrams/reference/sql/update/#syntax
• Follow-up for sbroad!485 (merged)