Support SARIF output

[kimburgess]

SARIF provides a standard output format for static analysis tools, like ameba.

With the continued integration of security tools into GitHub, there may be a lot of auxiliary functionality that can be gained by providing an associated formatter. This article has some nice examples of this.

This become particularly useful when combined with crystal-ameba/ameba-security#1.

Happy to help out with work on this if it's of interest.

[veelenga]

@kimburgess looking great. This can be implemented using a separate formatter. Here is a list of available formatters:

https://github.com/crystal-ameba/ameba/tree/master/src/ameba/formatter

If you feel happy to help, please take a look.