Refactor DI container for better structure and clarity

- Moved `TSinjex` class to `classes` directory for better organization.
- Updated imports across the codebase to reflect the new location of `TSinjex`.
- Introduced `Identifier` type to standardize dependency identifiers.
- Enhanced JSDoc comments for improved clarity and consistency.
- Adjusted error messages for `DependencyResolutionError` to provide clearer information.
- Updated and expanded decorator and function types to use `Identifier` type.

src/__tests__/DIContainer.test.ts

@@ -1,4 +1,4 @@
 import { test_IDIContainer } from './IDIContainer.spec';
-import { TSinjex } from '../TSinjex';
+import { TSinjex } from '../classes/TSinjex';
 
 test_IDIContainer(TSinjex);