Move ESLint environment configuration into `.eslintrc` (#2051)

js/.eslintrc

@@ -0,0 +1,6 @@
+{
+  "env": {
+    "browser": true,
+    "node": false
+  },
+}

js/modules/.eslintrc

@@ -0,0 +1,10 @@
+{
+  "env": {
+    "browser": false,
+    "commonjs": true,
+    "node": false
+  },
+  "globals": {
+    "console": true
+  }
+}