Print the model name as part of layer_utils.print_summary (aka model.summary)

CURRENT:
_________________________________________________________________
Layer (type)                 Output Shape              Param #
=================================================================
model_1_input (InputLayer)   [(None, 128)]             0

PROPOSED
_________________________________________________________________
Model: "part_of_speech_tagger"
Layer (type)                 Output Shape              Param #
=================================================================
model_1_input (InputLayer)   [(None, 128)]             0
PiperOrigin-RevId: 230427583