Create ways for HyperTransformer to know which transformers to apply to each data type

[amontanez24]

Problem Description

Since RDT will be expanding the number of data types it supports, we will need a new way for the HyperTransformer to determine which transformers to apply to a specific data type. We propose the following additions:

1. A function, get_transformers_by_type, which iterates over all the existing Transformers and calls the get_input_type method to create a dictionary that indicates which transformers work with which data type.
2. A DEFAULT_TRANSFORMERS dict which may indicate what the default transformer for each data type is.
3. If a data type is not in the DEFAULT_TRANSFORMERS dictionary, the first transformer found is "the default".

[kveerama]

@amontanez24 in the above formulation, would this method in hypertransformer simply return a transformer which can process the input_type regardless whether or not that transformer output_type is ready for ML or not?