Define the initial stable and experimental model sets for DeepTab

[mkumar73]

DeepTab currently exposes many tabular models, but it is not yet clear which ones are part of the stable core and which ones are still under evaluation. This issue defines the initial split and makes it official.

For the public version of this split, use:

• Stable: Mambular, TabM, NODE, FTTransformer, MLP, ResNet, TabTransformer, MambaTab, TabulaRNN, MambAttention, NDTF, SAINT, AutoInt, TabR
• Experimental: ModernNCA, Tangos, Trompt