Make TFMOT model files available

[alanchiao]

Motivation

Some people are interested in directly using or examining the models described under the overview pages of the different techniques under https://www.tensorflow.org/model_optimization.

Describe the feature

This is a master tracker for this. As people request for them, we can share them if readily available. Eventually, It would be best to host these models on
TFHub or a standardized location. This is useful for each model only if we can point them to an open source pipeline to reproduce the results also, though if users are aware of such pipelines and only need the model files, they can mention that also.

Technique:

• Pruning models: not readily available
• Quantization models: mostly readily available
• Clustering models: comment on Make TFMOT Clustering Model Files Available #530