Binarize QE models and make tool to do that

[kpu]

@mfomicheva e-mailed some JSON files which I have now checked in: 962d419

As @mfomicheva wrote in a follow up, these need to be binarized. The documentation refers to this thing:

https://github.com/abarbosa94/bergamot-translator/blob/quality-estimator-update/src/tests/units/quality_estimator_tests.cpp#L43

Can we get a proper tool for that? It doesn't have to be a full-on JSON parsing thing, but the values shouldn't be hard-coded in the C++. Binarized models are more important though.

[kpu]

@mfomicheva Thanks for the repo https://github.com/browsermt/quality-estimation with QE training and soon the binarizer.

@felipesantosk @mfomicheva Can you binarize the 3 JSON files and submit a PR to this repo (students) with the binary files? (One of them is done already.)