Refactor to improve iterations

- Use function abstractions (such as map, reduce, filter etc.) over
  for-of loops to gain benefits of having less side effects and easier
  readability.
- Enable `downLevelIterations` for writing modern code with lazy evaluation.
- Refactor for of loops to named abstractions to clearly express their
  intentions without needing to analyse the loop itself.
- Add missing cases for changes that had no tests.

src/presentation/components/Scripts/Menu/Selector/SelectionTypeHandler.ts

@@ -26,7 +26,7 @@ export class SelectionTypeHandler {
   }
 
   public getCurrentSelectionType(): SelectionType {
-    for (const [type, selector] of Array.from(selectors.entries())) {
+    for (const [type, selector] of selectors.entries()) {
       if (selector.isSelected(this.state)) {
         return type;
       }