Use github merge-results command when feature flag is enabled

lib/codeql.js

@@ -207,6 +207,7 @@ function setCodeQL(partialCodeql) {
         databaseExportDiagnostics: resolveFunction(partialCodeql, "databaseExportDiagnostics"),
         diagnosticsExport: resolveFunction(partialCodeql, "diagnosticsExport"),
         resolveExtractor: resolveFunction(partialCodeql, "resolveExtractor"),
+        mergeResults: resolveFunction(partialCodeql, "mergeResults"),
     };
     return cachedCodeQL;
 }
@@ -664,6 +665,22 @@ async function getCodeQLForCmd(cmd, checkVersion) {
             }).exec();
             return JSON.parse(extractorPath);
         },
+        async mergeResults(sarifFiles, outputFile, mergeRunsFromEqualCategory = false) {
+            const args = [
+                "github",
+                "merge-results",
+                "--output",
+                outputFile,
+                ...getExtraOptionsFromEnv(["github", "merge-results"]),
+            ];
+            for (const sarifFile of sarifFiles) {
+                args.push("--sarif", sarifFile);
+            }
+            if (mergeRunsFromEqualCategory) {
+                args.push("--sarif-merge-runs-from-equal-category");
+            }
+            await new toolrunner.ToolRunner(cmd, args).exec();
+        },
     };
     // To ensure that status reports include the CodeQL CLI version wherever
     // possible, we want to call getVersion(), which populates the version value