Ignore inferred dtype if encoder is manually provided.

[paxcema]

If a user manually specifies encoders, for example from MindsDB:

create predictor mindsdb.camber_8
from files
(select * from doubleWishbone)
predict Camber
using
encoders.Kz.module = 'NumericEncoder',
encoders.Cz.module = 'NumericEncoder',
encoders.F0z.module = 'NumericEncoder',
encoders.Hmax.module = 'NumericEncoder',
encoders.Camber.module = 'NumericEncoder';

We should be overriding the encoder (of course), but also the inferred dtype to the one supported by the manually specified encoder.