Implement SLICE function

[Kwontaehwon]

resolved #1307

Description

Implement SLICE function that return subsets of list.
Support both positive and negative start value

• If start value over the list length, it returns empty list : []

INSERT INTO Test VALUES ('[1,2,3,4]');
SELECT SLICE(list, 100, 5) AS value FROM Test;

• If start value is negative and its absolute value is over the list length, it convert to index 0.

Example

SLICE(<list>, <start>, <length>)

[coveralls]

Pull Request Test Coverage Report for Build 5867995917

• 165 of 165 (100.0%) changed or added relevant lines in 6 files are covered.
• 34 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.06%) to 99.143%

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Files with Coverage Reduction	New Missed Lines	%
core/src/executor/validate.rs	1	99.24%
core/src/executor/evaluate/mod.rs	3	99.36%
core/src/executor/aggregate/mod.rs	30	84.21%

Totals
Change from base Build 5857086559:	-0.06%
Covered Lines:	48465
Relevant Lines:	48884

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💛 - Coveralls

[zmrdltl]

really good! The slice function will soon become a new feature. It would be nice if only very small changes were possible. Couldn't these parts be put together?

[Kwontaehwon]

I intended that when a negative index is given, if index remain negative even after adding the size of vector to convert it to a positive index, it falls outside the range of vector. So I change index to 0.

[panarch]

Looks all great!
after the small conflict has been resolved, then let's ship this to the main!