Porting babel-plugin-transform-for-of-as-array into transform-for-of as an option (#6914)

packages/babel-plugin-transform-for-of/test/fixtures/error/invalid-option/actual.js

@@ -0,0 +1,4 @@
+let elm;
+for (elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/error/invalid-option/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": [["transform-for-of", { "assumeArray": true, "loose": true}]],
+  "throws": "The loose and assumeArray options cannot be used together in @babel/plugin-transform-for-of"
+}