Fix hash node rel

[andyfengHKU]

This PR fixes the bug when hashing NODE/REL where there is no dependent key.

We don't support hashing STRUCT, so hashing NODE/REL we always rewrite as hashing INTERNAL_ID and treat NODE/REL as dependent key i.e. payload. This rewrite fails for UNION because we don't have a way to rewrite the projection list of each subquery under UNION (technically we can but this is not the right way to approach the problem).

This PR adds hash function and compare function for NODE/REL data type.

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (2d1acf4) 89.42% compared to head (959229d) 89.45%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2192      +/-   ##
==========================================
+ Coverage   89.42%   89.45%   +0.03%     
==========================================
  Files        1007     1007              
  Lines       36292    36314      +22     
==========================================
+ Hits        32453    32485      +32     
+ Misses       3839     3829      -10     

Files	Coverage Δ
src/binder/bind/bind_projection_clause.cpp	93.33% <ø> (-0.05%)	⬇️
src/function/vector_hash_functions.cpp	90.00% <100.00%> (+3.46%)	⬆️
...rocessor/operator/aggregate/aggregate_hash_table.h	77.77% <ø> (-4.05%)	⬇️
src/optimizer/agg_key_dependency_optimizer.cpp	100.00% <100.00%> (ø)
...cessor/operator/aggregate/aggregate_hash_table.cpp	84.83% <82.22%> (+0.69%)	⬆️

... and 1 file with indirect coverage changes

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