[ENH] Implement `load_model` function for deep learning based regression ensemble models

[inclinedadarsh]

Describe the feature or idea you want to propose

Like #2436 (PR #2631), the regression module's deep learning submodule also contains the ensemble models InceptionTimeRegressor and LITETimeRegressor. Upon closer inspection, I discovered that they don't have the load_model function implemented either.

Describe your proposed solution

Implement load_model function for InceptionTimeRegressor and LITETimeRegressor models.

Checkout #2436 (comment) for more information regarding the suggested implementation.

Describe alternatives you've considered, if relevant

No response

Additional context

Would love to work on this issue, similar to #2436