Add GROUP BY alias rendering to ClickHouse SQLAlchemy compiler

[joe-clickhouse]

Summary

ClickHouse resolves SELECT aliases inside GROUP BY expressions which causes circular reference errors when an alias shadows a source column name. For example

SELECT toStartOfDay(toDateTime(time)) AS time
...
GROUP BY toStartOfDay(toDateTime(time))

fails because time in the expression resolves to the alias, not the column.

This PR adds group_by_clause and visit_label overrides to ChStatementCompiler so that labeled expressions in GROUP BY render as their alias name instead of the full expression. Note that SELECT and ORDER BY rendering is unaffected.

This fixes the root cause and underlying issue behind apache/superset#33551

Consequently, this should eliminate the need for Superset's alias-mangling workaround that appends hash suffixes to all ClickHouse column aliases to avoid these GROUP BY collisions.

To fully close the loop here I'll need to close apache/superset#34091 and then open another PR that no-ops or removes the current _mutate_label behavior and then require a version of ciikchouse-connect in superset greater than or equal to whatever version we cut this release in.

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG

[villebro]

LGTM, the Superset community will definitely ❤️ this improvement!

[joe-clickhouse]

Tested end to end by:

1. ripping out the superset mutation logic in the CH db engine spec
2. used this local clickhouse-connect with the group by rendering

The chart renders correctly in the UI and the rendered SQL is as follows:

SELECT
  dateTrunc('DAY', toDateTime(dateTrunc('DAY', dt))) AS "startOfDay",
  sum(number) AS "sum(number)"
FROM "default"."test_dates"
GROUP BY
  "startOfDay"
ORDER BY
  "sum(number)" DESC
LIMIT 10000

[joe-clickhouse]

Also worth noting that this change is backwards compatible with superset mutation logic. This GROUP BY change operates at the rendering level. So it doesn't care if the alias is time or time_b1bc24. However, once removing the mutation logic from superset, we'll want to pin clickhouse-connect >= whatever release this change makes it into.