Make sarifFinalFile folder customisable

Currently defaults to `${project.build.directory}` but should be configurable, just as the [`<xmlOutputDirectory>`](https://spotbugs.github.io/spotbugs-maven-plugin/spotbugs-mojo.html#xmlOutputDirectory) and [`<spotbugsXmlOutputDirectory>`](https://spotbugs.github.io/spotbugs-maven-plugin/spotbugs-mojo.html#spotbugsXmlOutputDirectory) parameters allow.