Don't limit virtual column output types

As of Druid 24.0.0, virtual columns are no longer restricted to LONG,
FLOAT, DOUBLE and STRING.

Also don't upcase the type name. For simple type names, Druid does
that for us, and for complex type names, it's not necessarily
appropriate.

lib/panoramix/query.ex

@@ -788,12 +788,7 @@ defmodule Panoramix.Query do
             expression: expression,
             output_type: output_type
           ] do
-      output_type = String.upcase(String.Chars.to_string(output_type))
-
-      unless output_type in ["LONG", "FLOAT", "DOUBLE", "STRING"] do
-        raise ArgumentError,
-              "Unexpected output type #{output_type}, expected one of :long, :float, :double, :string"
-      end
+      output_type = String.Chars.to_string(output_type)
 
       %{
         "type" => "expression",