Support NUMBER as number in JSON functions

Certain JSON functions have special treatment for number types, but they lack support for NUMBER

e.g.

SELECT 
  json_object('k' VALUE DECIMAL '1.2'), -- {"k":1.2}
  json_object('k' VALUE NUMBER '1.2'); -- {"k":"1.2"}

This also applies to

• json_array(CAST(1 AS number))
• json_value('1', 'lax $' RETURNING number)