Refactor to enforce strictNullChecks

This commit applies `strictNullChecks` to the entire codebase to improve
maintainability and type safety. Key changes include:

- Remove some explicit null-checks where unnecessary.
- Add necessary null-checks.
- Refactor static factory functions for a more functional approach.
- Improve some test names and contexts for better debugging.
- Add unit tests for any additional logic introduced.
- Refactor `createPositionFromRegexFullMatch` to its own function as the
  logic is reused.
- Prefer `find` prefix on functions that may return `undefined` and
  `get` prefix for those that always return a value.

tests/unit/shared/Stubs/DelaySchedulerStub.ts

@@ -1,7 +1,7 @@
 import { DelayScheduler } from '@/presentation/components/Scripts/View/Tree/TreeView/Rendering/DelayScheduler';
 
 export class DelaySchedulerStub implements DelayScheduler {
-  public nextCallback: () => void | undefined = undefined;
+  public nextCallback: (() => void) | undefined = undefined;
 
   public scheduleNext(callback: () => void): void {
     this.nextCallback = callback;