Create an internal dictionary for BaseDecisionTree

[adam2392]

problem

Rn, we have to override and copy a lot of custom code to make fit and partial_fit work in subclasses of BaseDecisionTree inside sktree.

possible soln

We should track the kwarg parameters needed to instantiate the:

• criterion
• splitter
• tree

These should be then easily accessible in subclasses. E.g.

class BaseDecisionTree
      _criterion_kwargs = ['n_samples', ...']
      _splitter_kwargs = ['criterion', 'max_features', ...]
...

Then ideally a subclass just has to add these additional kwargs to the __init__ structure and then override the corresponding _criterion/splitter/tree_kwargs.

cc: @PSSF23 from our discussion