fix(cubesql): Generate typed null literals

[mcheshkov]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made (if issue reference is not provided)

This is to avoid expressions like SUM(NULL), which are ambiguous in PostgreSQL

[codecov]

Codecov Report

Attention: Patch coverage is 60.16949% with 47 lines in your changes missing coverage. Please review.

Project coverage is 83.65%. Comparing base (57932fc) to head (eed7de2).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...t/cubesql/cubesql/src/compile/engine/df/wrapper.rs	41.97%	47 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9238      +/-   ##
==========================================
- Coverage   83.66%   83.65%   -0.01%     
==========================================
  Files         227      227              
  Lines       81688    81773      +85     
==========================================
+ Hits        68346    68409      +63     
- Misses      13342    13364      +22     

Flag	Coverage Δ
cubesql	83.65% <60.16%> (-0.01%)	⬇️

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