experiments with vectorized aggregation

[akuzm]

Parts:

• Don't copy compressed slot to compressed batch struct #6806
• vectorized aggregation as separate plan node #6784
• Treat segmentby columns same as compressed columns with default value #6817
• Avoid projection more often in DecompressChunk node #6859

[codecov]

Codecov Report

Attention: Patch coverage is 85.51913% with 53 lines in your changes are missing coverage. Please review.

Project coverage is 80.68%. Comparing base (59f50f2) to head (8ad6967).
Report is 129 commits behind head on main.

Files	Patch %	Lines
tsl/src/nodes/vector_agg/plan.c	75.89%	8 Missing and 19 partials ⚠️
tsl/src/nodes/vector_agg/exec.c	90.00%	0 Missing and 9 partials ⚠️
...l/src/nodes/vector_agg/grouping_policy_segmentby.c	88.15%	0 Missing and 9 partials ⚠️
tsl/src/nodes/vector_agg/grouping_policy_all.c	91.83%	0 Missing and 4 partials ⚠️
tsl/src/nodes/vector_agg/functions.c	89.65%	0 Missing and 3 partials ⚠️
tsl/src/planner.c	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6793      +/-   ##
==========================================
+ Coverage   80.06%   80.68%   +0.61%     
==========================================
  Files         190      200      +10     
  Lines       37181    37064     -117     
  Branches     9450     9670     +220     
==========================================
+ Hits        29770    29906     +136     
- Misses       2997     3236     +239     
+ Partials     4414     3922     -492     

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