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/application/Context/State/Code/Generation/CodeBuilder.ts

@@ -17,9 +17,7 @@ export abstract class CodeBuilder implements ICodeBuilder {
       return this;
     }
     const lines = code.match(/[^\r\n]+/g);
-    for (const line of lines) {
-      this.lines.push(line);
-    }
+    this.lines.push(...lines);
     return this;
   }