artifact.sourceLanguage property (§3.24.10) for SARIF itself

[davidmalcolm]

Appendix J doesn't seem to have an entry for SARIF itself; the closest is "json".

Consider a tool for processing .sarif files that encounters an error (e.g. missing a required property), and which report its own status using SARIF.

I'm thinking of using "sarif" as the name.

Use case: I'm writing a sarif-replay tool that reads diagnostics from .sarif files and "replays" them as if them were GCC diagnostics (see https://gcc.gnu.org/wiki/libdiagnostics)