Fix types

[archiewood]

Write: COPY TO

COPY TO can copy any type from duckdb

• NULLs write an empty cell,
• unless in an array in which case print NULL in place

Read: read_gsheet()

• Reads into either bool, varchar or double
  All numbers are read as doubles irrespective of size or if they are integers
• Uses the first row for type detection. Fails if a varchar column has a number in the first row