DRAFT: Add Tabular Learner

[jeremiahpslewis]

This pull request adds a Tabular Learner to the project. The Tabular Learner is used for reinforcement learning tasks and includes implementations for TDLearner, TabularVApproximator, and TabularQApproximator.

[codecov]

Codecov Report

Attention: Patch coverage is 28.57143% with 25 lines in your changes are missing coverage. Please review.

Project coverage is 24.49%. Comparing base (a6623a8) to head (be6e3b3).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1033       +/-   ##
===========================================
+ Coverage   12.74%   24.49%   +11.75%     
===========================================
  Files         229      232        +3     
  Lines        7903     7876       -27     
===========================================
+ Hits         1007     1929      +922     
+ Misses       6896     5947      -949     

Files	Coverage Δ
...ningCore/src/policies/learners/abstract_learner.jl	0.00% <ø> (ø)
...earningCore/test/policies/learners/approximator.jl	100.00% <ø> (ø)
...LearningCore/src/policies/learners/approximator.jl	85.71% <85.71%> (ø)
...Core/src/policies/learners/tabular_approximator.jl	64.28% <50.00%> (+64.28%)	⬆️
...ntLearningZoo/src/algorithms/tabular/td_learner.jl	0.00% <0.00%> (ø)

... and 25 files with indirect coverage changes