This PR adds support for the .decimal_sep and .thousand_sep options that can be used in the CLI to configure how these are rendered. Note that this is only respected in duckbox mode currently. Example usage:

.decimal_sep ,
.thousand_sep _
SELECT 12345.6;
┌──────────────┐
│   12345.6    │
│ decimal(6,1) │
├──────────────┤
│     12_345,6 │
└──────────────┘

Note that there is one restriction - this currently does not work with nested types yet but only for numbers at the top-level.