merge all .sarif files at the end of the QL-for-QL workflow

ql/scripts/merge-sarif.js

@@ -0,0 +1,26 @@
+var fs = require("fs");
+
+// first a  list of files to merge, and the last argument is the output file.
+async function main(files) {
+  const inputs = files
+    .slice(0, -1)
+    .map((file) => fs.readFileSync(file))
+    .map((data) => JSON.parse(data));
+  const out = inputs[0]; // just arbitrarily take the first one
+  const outFile = files[files.length - 1];
+
+  const combinedResults = [];
+
+  for (const sarif of inputs) {
+    combinedResults.push(...sarif.runs[0].results);
+  }
+
+  out.runs[0].artifacts = []; // the indexes in these won't make sense, so I hope this works.
+  out.runs[0].results = combinedResults;
+
+  // workaround until https://github.com/microsoft/sarif-vscode-extension/pull/436/ is part of a release
+  out["$schema"] = "https://raw.githubusercontent.com/oasis-tcs/sarif-spec/master/Schemata/sarif-schema-2.1.0"; 
+
+  fs.writeFileSync(outFile, JSON.stringify(out, null, 2));
+}
+main(process.argv.splice(2));