Support dumping json empty configuration at kompile time

[ehildenb]

Currently when using the pyk library, we have to get a "blank" configuration to use for manipulating K terms and stuff. To produce this, I run a garbage proof out to depth 0, and strip the configuration. For example, I may run this proof out to depth 0:

claim <k> #execute => . ... </k>

This will give me a configuration that looks like this:

<generatedTop>
  <kevm>
    <k> #execute ... </k>
    <mode> _0 </mode>
    <schedule> _1 </schedule>
    ...
</generatedTop>

Which I then strip to look like:

<generatedTop>
  <kevm>
    <k> K_CELL </k>
    <mode> MODE_CELL </mode>
    <schedule> SCHEDULE_CELL </schedule>
    ...
</generatedTop>

So it would be nice if when I call kompile --emit-json, it dumped the empty configuration to a file empty-config.json in the *-kompiled directory. Then I could just read that file off instead using this ad-hoc way of generating it.

[radumereuta]

https://github.com/runtimeverification/k/blob/master/haskell-backend/src/main/java/org/kframework/backend/haskell/HaskellRewriter.java#L353
Modify this module and try to dump it as json.