Add list_sum and list_sort functions

[gaurav8297]

Added functions:

1. list_sort(list)

Sorts the elements of the list.

Examples:

-- default sort order and default NULL sort order
Return list_sort([1, 3, NULL, 5, NULL, -5])
----
[NULL, NULL, -5, 1, 3, 5]

-- only providing the sort order
Return list_sort([1, 3, NULL, 2], 'ASC')
----
[NULL, 1, 2, 3]

-- providing the sort order and the NULL sort order
Return list_sort([1, 3, NULL, 2], 'DESC', 'NULLS FIRST')
----
[NULL, 3, 2, 1]

2. list_sum(list)

Returns the sum of all elements in the list

[codecov]

Codecov Report

Patch coverage: 92.30% and no project coverage change.

Comparison is base (4f02b2d) 91.95% compared to head (31d9516) 91.96%.

❗ Current head 31d9516 differs from pull request most recent head f987264. Consider uploading reports for the commit f987264 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #1529    +/-   ##
========================================
  Coverage   91.95%   91.96%            
========================================
  Files         687      689     +2     
  Lines       24502    24665   +163     
========================================
+ Hits        22532    22683   +151     
- Misses       1970     1982    +12     

Impacted Files	Coverage Δ
src/function/vector_list_operation.cpp	90.32% <88.52%> (-0.59%)	⬇️
...ude/function/list/operations/list_sort_operation.h	95.45% <95.45%> (ø)
src/function/built_in_vector_operations.cpp	96.02% <100.00%> (+0.02%)	⬆️
...lude/function/list/operations/list_sum_operation.h	100.00% <100.00%> (ø)
src/include/function/list/vector_list_operations.h	97.36% <100.00%> (+0.14%)	⬆️
src/include/function/unary_operation_executor.h	72.22% <100.00%> (+1.63%)	⬆️

... and 13 files with indirect coverage changes

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[acquamarin]

1. See my comment about refactoring the list_sort operation.
2. Add more tests to improve test coverages.
3. We already have an orderBy operator which implements our own sorting algorithm. We should reuse the orderBy operator inside list_sort. Can you open an issue about this?