Implement CQExternal extra conversion

[jnsrnhld]

-- example query
with "external_ids" as (select '1'                                                         as "primary_id",
                               datemultirange(daterange('2012-01-01', '2012-01-01', '[]')) as "dates"
                        from (select 1) as "nop_table"
                        union all
                        select '3'                                                         as "primary_id",
                               datemultirange(daterange('2013-11-10', '2013-11-10', '[]')) as "dates"
                        from (select 1) as "nop_table"
                        union all
                        select '6'                                                         as "primary_id",
                               datemultirange(daterange('2013-11-10', '2013-11-10', '[]')) as "dates"
                        from (select 1) as "nop_table"),
     "external_extra" as (select '1' as "primary_id",
                                 '1' as "payload_1",
                                 '2' as "payload_2",
                                 '3' as "payload_3",
                                 '4' as "payload_4",
                                 '5' as "payload_5",
                                 '6' as "payload_6",
                                 '7' as "payload_7",
                                 '8' as "payload_8"
                          from (select 1) as "nop_table"
                          union all
                          select '3'               as "primary_id",
                                 '1' || '�' || '1' as "payload_1",
                                 '2' || '�' || '2' as "payload_2",
                                 '3' || '�' || '3' as "payload_3",
                                 '4' || '�' || '4' as "payload_4",
                                 '5' || '�' || '5' as "payload_5",
                                 '6' || '�' || '6' as "payload_6",
                                 '7' || '�' || '7' as "payload_7",
                                 '8' || '�' || '8' as "payload_8"
                          from (select 1) as "nop_table"
                          union all
                          select '6' as "primary_id",
                                 '1' as "payload_1",
                                 '2' as "payload_2",
                                 '3' as "payload_3",
                                 '4' as "payload_4",
                                 '5' as "payload_5",
                                 '6' as "payload_6",
                                 '7' as "payload_7",
                                 '8' as "payload_8"
                          from (select 1) as "nop_table")
select "external_ids"."primary_id",
       replace(
               (range_agg("external_ids"."dates"))::varchar,
               'infinity',
               '∞'
       ) as "dates",
       "external_extra"."payload_1",
       "external_extra"."payload_2",
       "external_extra"."payload_3",
       "external_extra"."payload_4",
       "external_extra"."payload_5",
       "external_extra"."payload_6",
       "external_extra"."payload_7",
       "external_extra"."payload_8"
from "external_ids"
         join "external_extra"
              on "external_ids"."primary_id" = "external_extra"."primary_id"
group by "external_ids"."primary_id",
         "external_extra"."payload_1",
         "external_extra"."payload_2",
         "external_extra"."payload_3",
         "external_extra"."payload_4",
         "external_extra"."payload_5",
         "external_extra"."payload_6",
         "external_extra"."payload_7",
         "external_extra"."payload_8"