Change expression scan to dummy scan

[andyfengHKU]

This PR is a follow up of #1889. We enforce the invariant that a literal expression is always evaluated rather than referenced

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03% 🎉

Comparison is base (3c40a45) 89.44% compared to head (45a6060) 89.47%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1892      +/-   ##
==========================================
+ Coverage   89.44%   89.47%   +0.03%     
==========================================
  Files         839      839              
  Lines       30679    30699      +20     
==========================================
+ Hits        27441    27469      +28     
+ Misses       3238     3230       -8     

Files Changed	Coverage Δ
...ical_plan/logical_operator/base_logical_operator.h	90.00% <ø> (ø)
src/include/processor/mapper/plan_mapper.h	100.00% <ø> (ø)
src/optimizer/filter_push_down_optimizer.cpp	99.01% <ø> (ø)
.../processor/mapper/create_factorized_table_scan.cpp	100.00% <ø> (ø)
...logical_plan/logical_operator/logical_dummy_scan.h	100.00% <100.00%> (ø)
src/include/processor/operator/index_scan.h	100.00% <100.00%> (ø)
src/planner/operator/base_logical_operator.cpp	73.23% <100.00%> (ø)
src/planner/operator/logical_dummy_scan.cpp	100.00% <100.00%> (ø)
src/planner/operator/logical_scan_node.cpp	100.00% <100.00%> (ø)
src/planner/query_planner.cpp	93.52% <100.00%> (-0.08%)	⬇️
... and 4 more

... and 5 files with indirect coverage changes

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