[AQUMV] Support DISTINCT clause on origin query.

[avamingli]

SELECT DISTINCT clause references are processed in target list, open it on origin query.
DISTINCT in aggregation and Group By DISTINCT are already supported, add cases to verify that.

create incremental materialized view mv as
  select c1 as mc1, c2 as mc2, c3 as mc3, c4 as mc4
  from t1 where c1 > 90;

Origin querys:

  select DISTINCT c2 from t1 where c1 > 90;

  select count(DISTINCT c2) from t1 where c1 > 90;

  select c1, c2, c3, sum(c4) from t1 where c1 > 90
  group by DISTINCT rollup(c1, c2), rollup(c1, c3);

Could be rewritten to:

  select DISTINCT mc2 from mv;

  select count(DISTINCT mc2) from mv;

  select mc1, mc2, mc3, sum(mc4) from mv
  group by DISTINCT rollup(mc1, mc2), rollup(mc1, mc3);

Authored-by: Zhang Mingli avamingli@gmail.com

fix #ISSUE_Number

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[yjhjstz]

icw-orca-test failed.