Replace some common index based for loops with for-of loops

Replaces many loops of the form:

```js
for (let i = 0; i < elements.length; ++i) {
    const i = elements[i];
   ...
}
```

with:

```js
for (const element of elements) {
    ...
}
```

Mix of a horrible regex based find/replace and manual touch ups

extensions/typescript-language-features/src/features/fileConfigurationManager.ts

@@ -13,8 +13,7 @@ import { ResourceMap } from '../utils/resourceMap';
 
 function objsAreEqual<T>(a: T, b: T): boolean {
 	let keys = Object.keys(a);
-	for (let i = 0; i < keys.length; i++) {
-		let key = keys[i];
+	for (const key of keys) {
 		if ((a as any)[key] !== (b as any)[key]) {
 			return false;
 		}