ConfigMagic should use AbstractMagic.ParseInputParameters to accept both key=value and JSON formats

[rmshaffer]

Describe the issue The parameters to %config are not handled using the common argument-parsing code that is used by most of the other IQ# magic commands. As a result, there are slight differences in behavior. Most notably, %config does not support JSON-encoded parameters.

Desired behavior The custom argument-parsing code in ConfigMagic should be replaced with a call to AbstractMagic.ParseInputParameters, following the example of most of the other IQ# magic commands. e.g., see SimulateMagic and EstimateMagic.

Additional context This was raised in #322. As part of fixing this, we should update the calls to %config in iqsharp.py to use json.dumps(map_tuples(...)), rather than having custom serialization code specifically for %config.