fix(snowflake): bring back where filter support in group_concat; fix array_agg ordering

[cpcloud]

Fixes two bugs introduced in #9729.

• where handling was accidentally removed. This PR brings it back.
• array_agg must be ordered using WITHIN GROUP, it doesn't accept a trailing ORDER BY in the call.

[cpcloud]

Locally all green, merging:

…/ibis on  snowflake-fix-order is 📦 v9.2.0 via 🐍 v3.10.14 via ❄️   impure (ibis-3.10.14-env)
❯ pytest -m snowflake -n 8 --dist loadgroup -q
bringing up nodes...
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1606 passed, 10 skipped, 223 xfailed in 191.81s (0:03:11)