Save model data into more compact and efficient binary format

[antimora]

Feature description

Save model data into more compact and efficient binary format, such as bincode or messagepack

Feature motivation

Saving large data into JSON is not efficient (large files and memory requirements). Additionally, saving float numbers to JSON and getting from is not precise because of some intermediate number type conversion (some may consider as data loss).

The efficiency deserialization (space and speed) becomes more important for applications that want to bundle model data into the code, using include_bytes! macro.

(Optional) Suggest a Solution

In our binary format, we should include format and version information the the output for future compatibility and support.

messagepack has more language support and could be used as our de-facto export format. Bincode seems to work on rust.

Action Item

Remove/modify examples/mnist-inference-web/build.rs once we have built-in facility to export data directly to binary format.