[MLH] Pass options via a json file instead of command line arguments

[arthaud]

Mariana Trench consists of:

• The shim, a small python script, which parses user-provided command line options and calls the binary
• The C++ binary, which actually performs the analysis.

To pass the user-provided options from python to C++, we currently build a very long command from python:
https://github.com/facebook/mariana-trench/blob/main/shim/shim.py#L610-L748
We then parse those options from C++:
https://github.com/facebook/mariana-trench/blob/main/source/Options.cpp#L151-L306

While this works fine, we risk running into the maximum size of a command line (although unlikely): https://unix.stackexchange.com/questions/120642/what-defines-the-maximum-size-for-a-command-single-argument
It is also painful to debug problems with argument passing.

For these reasons, we would like to implement a new way of passing arguments:
The shim should create a temporary json file containing all parameters, and the C++ binary would just parse that file.