Emit json definitions when kompiling

[ehildenb]

• Improvements to pyk serialization to files when running {krun,kast,kprove}JSON functions.
• Add function which splits configuration from substitution to pyk.
• Add definition JSON serialization/deserialization methods.
• Add --emit-json option to Kompile which emits the json serialized definition to the -kompiled directory (and test of it).

[dwightguth]

What exactly is this being used for? I highly doubt it is going to be possible to serialize, deserialize, and then compile or krun using the result. Not without more work to ensure a faithful rendering.

[ehildenb]

@dwightguth I'm going to use it to build Python unparsers for KLabels automatically using pyks underbarUnparsing function, so that I can get rid of the tons of boilerplate in places like https://github.com/runtimeverification/polkadot-verification/blob/a50120c8493805d4146af4182bfb9dec44d298e0/pykWasm.py#L35 and https://github.com/runtimeverification/beacon-chain-spec/blob/a0975944c17537ecd070051cc08a387b2dda9403/buildConfig.py#L76

I do eventually want to be able to re-load definitions, but I removed the --input json option for komplie from this PR because it is not working yet. That's lower priority than having the definition available in structured form for external tools.

[dwightguth]

Looks reasonable if you don't intend to deserialize it in the frontend yet.