chore: prettier json output and output improvements

[thschue]

📑 Description

• Decouple analysis and output (analyze -> AI analysis -> output)
• Add structure for Json Output
• Add problem count and overall status to JSON, use jsonIndent to make it better readable
• Report "No issues found" in text output if nothing is found
• Use this structure for success too
• Move output generation to analysis to make it re-usable e.g. in API, operator
• First tests for json output

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed