Add simple json report generation

[tuturu-tech]

Added very simple json report generation (only lines found/covered)

Issues:

• Error var is overridden, looking for guidance on how best to handle this
• html path is modified in order to replace the file name, looking for guidance here as well
• Currently not generating branches/functions coverage

[montyly]

@tuturu-tech can you fix the issues reported by golangci-lint?

You can look at https://github.com/crytic/medusa/blob/01c8d9efc40ac13ae937a7cef3f1999290dca7b7/CONTRIBUTING.md#linters to see how to install and run it

[anishnaik]

I don't think we need this anymore, closing.