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/shared/Assertions/ExpectThrowsAsync.ts

@@ -1,30 +0,0 @@
-import { expect } from 'vitest';
-
-export async function expectThrowsAsync(
-  method: () => Promise<unknown>,
-  errorMessage: string,
-) {
-  let error: Error | undefined;
-  try {
-    await method();
-  } catch (err) {
-    error = err;
-  }
-  expect(error).toBeDefined();
-  expect(error).to.be.an(Error.name);
-  if (errorMessage) {
-    expect(error.message).to.equal(errorMessage);
-  }
-}
-
-export async function expectDoesNotThrowAsync(
-  method: () => Promise<unknown>,
-) {
-  let error: Error | undefined;
-  try {
-    await method();
-  } catch (err) {
-    error = err;
-  }
-  expect(error).toBeUndefined();
-}