SARIF 2.1.0 messages with placeholders

[KalleOlaviNiemitalo]

SarifParser ignores the message.arguments property ([SARIF-v2.1.0] §3.11.11). It should locate the placeholders in the message string ([SARIF-v2.1.0] §3.11.5) and replace them with those arguments, and decode any {{ or }} pairs that represent curly braces outside of placeholders.

Please see #157 (comment) for a sample log with placeholders and arguments.

[tomasbjerre]

I think this is implemented now.