Add eslint as linter and add linter workflow

eslint.config.mjs

@@ -0,0 +1,32 @@
+import jest from "eslint-plugin-jest";
+import globals from "globals";
+export default [{
+    plugins: {
+        jest,
+    },
+
+    languageOptions: {
+        globals: {
+            ...globals.jest,
+            ...jest.environments.globals.globals,
+        },
+    },
+
+    rules: {
+        "no-fallthrough": "error",
+        "no-case-declarations": "error",
+        "no-unused-vars": "warn"
+    },
+    
+},
+];
+
+
+
+
+// /** @type {import('eslint').Linter.Config[]} */
+// export default [
+//   {files: ["**/*.js"], languageOptions: {sourceType: "commonjs"}},
+//   {languageOptions: { globals: globals.node }},
+//   pluginJs.configs.recommended,
+// ];