Fix return functor windows compatibility

[andyfengHKU]

Windows doesn't have a good support to return function pointer. Previously we had to expose static functions in header files in order to return their pointer.

This PR changes return function pointer to set a functor reference. So we can wrap static functions inside class.

[codecov]

Codecov Report

Patch coverage: 95.57% and project coverage change: -0.03 ⚠️

Comparison is base (2478bc8) 91.93% compared to head (d0dcbd5) 91.91%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1586      +/-   ##
==========================================
- Coverage   91.93%   91.91%   -0.03%     
==========================================
  Files         703      703              
  Lines       25339    25515     +176     
==========================================
+ Hits        23295    23451     +156     
- Misses       2044     2064      +20     

Impacted Files	Coverage Δ
...ude/function/interval/vector_interval_operations.h	95.45% <ø> (ø)
...include/function/string/vector_string_operations.h	96.00% <ø> (ø)
...cessor/operator/aggregate/aggregate_hash_table.cpp	79.37% <60.00%> (-1.79%)	⬇️
src/function/vector_cast_operations.cpp	82.72% <88.23%> (-0.11%)	⬇️
...binder/bind_expression/bind_boolean_expression.cpp	100.00% <100.00%> (ø)
.../bind_expression/bind_null_operator_expression.cpp	100.00% <100.00%> (ø)
src/binder/expression_binder.cpp	97.33% <100.00%> (+0.03%)	⬆️
src/function/vector_boolean_operations.cpp	79.31% <100.00%> (+7.88%)	⬆️
src/function/vector_list_operation.cpp	89.89% <100.00%> (+0.22%)	⬆️
src/function/vector_null_operations.cpp	72.72% <100.00%> (+10.22%)	⬆️
... and 11 more

... and 1 file with indirect coverage changes

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