Changes to Foundational Time Series Model Multi Series Finetuning

added the new optional request property series/start_datetime

the model request property type changed from no type to string

the finetune_steps request property's min was set to 0.00

added the new optional request property hist_exog

added the new optional request property model_parameters

added the new optional request property multivariate

added the new optional request property series/X

added the new optional request property series/X_future

added the new optional request property series/categorical_exog

added the optional property detail/items/ctx to the response with the 422 status

added the optional property detail/items/input to the response with the 422 status