Some bug fixes in logical -> logical optimizer

[AlSchlo]

The logical -> logical optimizer was untested, this PR adds demo/test code for sanity checking during development. It ensures that the optimizer does not crash, and that the memo table gets populated with expressions (through prints).

This demo code will go away as we get a more robust testing framework & observation of the task graph.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.20388% with 7 lines in your changes missing coverage. Please review.

Project coverage is 88.1%. Comparing base (570efc9) to head (2dfc837).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
optd/src/demo/mod.rs	90.4%	4 Missing ⚠️
optd/src/optimizer/hir_cir/mod.rs	91.3%	2 Missing ⚠️
optd/src/optimizer/retriever.rs	0.0%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
optd/src/cir/rules.rs	50.0% <ø> (+50.0%)	⬆️
optd/src/memo/memory/implementation.rs	91.3% <100.0%> (+0.4%)	⬆️
optd/src/optimizer/handlers.rs	75.8% <100.0%> (+75.8%)	⬆️
optd/src/optimizer/jobs/execute.rs	60.1% <100.0%> (+60.1%)	⬆️
optd/src/optimizer/mod.rs	91.5% <100.0%> (+91.5%)	⬆️
optd/src/optimizer/tasks/launch.rs	97.1% <100.0%> (+97.1%)	⬆️
optd/src/optimizer/retriever.rs	17.6% <0.0%> (+17.6%)	⬆️
optd/src/optimizer/hir_cir/mod.rs	91.3% <91.3%> (ø)
optd/src/demo/mod.rs	90.4% <90.4%> (ø)

... and 16 files with indirect coverage changes

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