Exclude foreign keys from being used to generate prediction problems

[gsheni]

• Change "index" to "primary_key"
• Fixes duplicate prediction problem generation by hashing all possible prediction problems
• Allow Ops to restrict semantic tags

[codecov]

Codecov Report

Patch coverage: 92.20% and project coverage change: +0.17% 🎉

Comparison is base (1a538c0) 89.30% compared to head (779fc7c) 89.48%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #108      +/-   ##
==========================================
+ Coverage   89.30%   89.48%   +0.17%     
==========================================
  Files          26       26              
  Lines         851      894      +43     
==========================================
+ Hits          760      800      +40     
- Misses         91       94       +3     

Files Changed	Coverage Δ
trane/datasets/load_functions.py	100.00% <ø> (ø)
trane/ops/filter_ops.py	100.00% <ø> (ø)
trane/parsing/denormalize.py	93.44% <ø> (ø)
trane/core/prediction_problem.py	79.16% <76.92%> (-0.36%)	⬇️
trane/core/prediction_problem_generator.py	92.13% <85.71%> (-1.27%)	⬇️
trane/core/utils.py	85.96% <95.45%> (+5.70%)	⬆️
trane/ops/aggregation_ops.py	100.00% <100.00%> (ø)
trane/ops/op_base.py	98.00% <100.00%> (+0.12%)	⬆️
trane/typing/inference.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[gsheni]

Still need to add a few more unit tests and assertions