PivotTable: UUID type cells should get monospace styling

[rpbouman]

Right now the styling is all controlled through data-value-type, which gets the arrow data type name.

(Derivations can override it by setting a dataValueTypeOverride property, which is by the weekday and monthname derivations to override their integer data type with Utf8, which is the arrow string data type.)

UUID types are rendered as Utf8 (string) in arrow.
This is actually ok. The trick with dataValueTypeOverride does not really seem a good fit here.

A possible solution would be to add an additional SQL data type to the cells and use that instead of the arrow data type to control the styling, but this is not that easily available at the axisItem level (for member derivations we have to extract it)