[MLGO] Make TFLiteUtils throw an error if some features haven't been passed to the...

[MLGO] Make TFLiteUtils throw an error if some features haven't been passed to the model

In the Tensorflow C lib utilities, an error gets thrown if some features
haven't gotten passed into the model (due to differences in ordering
which now don't exist with the transition to TFLite). However, this is
not currently the case when using TFLiteUtils. This patch makes some
minor changes to throw an error when not all inputs of the model have
been passed, which when not handled will result in a seg fault within
TFLite.

Reviewed By: mtrofin

Differential Revision: https://reviews.llvm.org/D133451