RFE[format json1]: Add property holding shell script snippets

[jamacku]

For new checks and feature suggestions

• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Please add property holding shell script snippets into json1 format. It could be helpful for anyone trying to process the results of ShellCheck without access to the codebase used to generate the defects.

Example of such a case:

• json-parser: basic support for ShellCheck's JSON output csutils/csdiff#83

Note: csdiff is a tool for comparing code scan defect lists to find added or fixed defects.

In linked PR, we can process the json1 format taken from input, but since we have no information about the code that produced JSON, we cannot display it in a meaningful way. Having this information stored in JSON would be very useful.

Many thanks for considering my request. 👍

/cc @kdudka @lzaoral