[Enhancement] Support multiple DISTINCT aggregates for collect_list and array_agg

### Search before asking

- [X] I had searched in the [issues](https://github.com/apache/doris/issues?q=is%3Aissue) and found no similar issues.

### Description

When a single GROUP BY contains more than one DISTINCT aggregate and any of them
is `collect_list(distinct ...)` or `array_agg(distinct ...)`, planning fails with:

errCode = 2, ... can't support multi distinct.

`CheckMultiDistinct` rejects any distinct aggregate that does not implement
`SupportMultiDistinct`, and `collect_list` / `array_agg` do not implement it.
So queries like these cannot run:

select g, collect_list(distinct a), collect_list(distinct b) from t group by g;
select g, array_agg(distinct a), array_agg(distinct b) from t group by g;

Other aggregates (count, sum, sum0, group_concat) already support this through
the multi-distinct framework. `collect_list` and `array_agg` should too, via new
`multi_distinct_collect_list` and `multi_distinct_array_agg` functions.

### Solution

Add `multi_distinct_collect_list` / `multi_distinct_array_agg` and make
`CollectList` / `ArrayAgg` implement `SupportMultiDistinct`, plugging into the
existing multi-distinct rewrite (BE + FE).

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

Start by tracing CheckMultiDistinct and the existing multi-distinct implementations for count, sum, sum0, and group_concat. Then inspect CollectList and ArrayAgg across the FE and BE paths. Done means the new multi_distinct_collect_list and multi_distinct_array_agg functions participate in the rewrite and both DISTINCT aggregate query examples plan and run successfully.

Written by the indexing model from the issue text.