Refactor DI for simplicity and type safety

This commit improves the dependency injection mechanism by introducing a
custom `injectKey` function.

Key improvements are:

- Enforced type consistency during dependency registration and
  instantiation.
- Simplified injection process, abstracting away the complexity with a
  uniform API, regardless of the dependency's lifetime.
- Eliminated the possibility of `undefined` returns during dependency
  injection, promoting fail-fast behavior.
- Removed the necessity for type casting to `symbol` for injection keys
  in unit tests by using existing types.
- Consalidated imports, combining keys and injection functions in one
  `import` statement.

tests/unit/application/Context/ApplicationContextFactory.spec.ts

@@ -7,7 +7,7 @@ import { IApplication } from '@/domain/IApplication';
 import { RuntimeEnvironmentStub } from '@tests/unit/shared/Stubs/RuntimeEnvironmentStub';
 import { ApplicationStub } from '@tests/unit/shared/Stubs/ApplicationStub';
 import { CategoryCollectionStub } from '@tests/unit/shared/Stubs/CategoryCollectionStub';
-import { expectThrowsAsync } from '@tests/unit/shared/Assertions/ExpectThrowsAsync';
+import { expectThrowsAsync } from '@tests/shared/Assertions/ExpectThrowsAsync';
 
 describe('ApplicationContextFactory', () => {
   describe('buildContext', () => {