POC: Eliminate unnecessary group by keys (q35 in clickbench 1.35x faster)

[Rachelint]

Which issue does this PR close?

Closes #.

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[Rachelint]

It is really effective for query like q35 in clickbench.

// Before
Q35: SELECT "ClientIP", "ClientIP" - 1, "ClientIP" - 2, "ClientIP" - 3, COUNT(*) AS c FROM hits GROUP BY "ClientIP", "ClientIP" - 1, "ClientIP" - 2, "ClientIP" - 3 ORDER BY c DESC LIMIT 10;
Query 35 iteration 0 took 2371.1 ms and returned 10 rows

// After
Q35: SELECT "ClientIP", "ClientIP" - 1, "ClientIP" - 2, "ClientIP" - 3, COUNT(*) AS c FROM hits GROUP BY "ClientIP", "ClientIP" - 1, "ClientIP" - 2, "ClientIP" - 3 ORDER BY c DESC LIMIT 10;
Query 35 iteration 0 took 1491.4 ms and returned 10 rows

[Rachelint]

It's late today, plan to sort out codes and add test tomorrow.