Support sample weight col in Keras estimator

[irasit]

Is your feature request related to a problem? Please describe.
It seems we add the sample_weight_col in data loading of remote function, but I do not see the trainer actually using it in fit function here.

Describe the solution you'd like
According to this link, the proper way of doing that would be like
model.fit(x_train, y_train,
sample_weight=sample_weight,
batch_size=64,
epochs=5)