sql/to_date.md: new page

Summary

• expression.svg: add link to strftime
• sql/to_date.md: new page

Address changes from picodata!934 (merged)

Version: Picodata 24.3.0-81-ga2143d90 (picodata@a2143d90)

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• Close #234 (closed)
• Cherry-pick to: 24.3
• Staging:
  • https://docs.binary.picodata.io/picodata/asabirov_add_to_date_function/reference/sql/to_date/
  • https://docs.binary.picodata.io/picodata/asabirov_add_to_date_function/reference/ansi_sql/#additional_features
  • https://docs.binary.picodata.io/picodata/asabirov_add_to_date_function/sql_index/