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.

tests/unit/presentation/components/Scripts/View/Tree/ScriptNodeParser.spec.ts

@@ -63,7 +63,6 @@ describe('ScriptNodeParser', () => {
       expectSameScript(nodes[2], scripts[2]);
     });
   });
-
   it('parseAllCategories parses as expected', () => {
     // arrange
     const collection = new CategoryCollectionStub()