Provide a way to refresh columns from a Google Sheet

[twschiller]

User Story

• As a Mod Developer, I want to refresh the fields in the Append to Google Sheet brick so that I can wire up my data
• https://www.loom.com/share/fd18cd22d24f4031b5b7d61e073aadf3

Acceptance Criteria

• Tab Widget has a "refresh" button
• On refresh, available fields are updated
• TO DECIDE: if the sheet no longer has a header, should we 1) automatically delete that column, or 2) should we just set additionalProperties: true so the column is displayed and the user can remove it? I think the current behavior (e.g., if a field was removed while the Page Editor was closed) might be the property is just hidden and the mod has no way to delete the value

Related Code

• https://github.com/pixiebrix/pixiebrix-extension/blob/ca3e6f30755ec36700b72a6678aa06016ee44a40/src/contrib/google/sheets/ui/AppendSpreadsheetOptions.tsx#L155-L155