feat(tests): Check for specific error messages in test suite

[subha0319]

Implements #105.

Updates the TestExamples test suite to check for specific error messages.
The test harness now reads a comment tag // @ExpectedError: "Error Title" from files that are expected to fail and validates the actual error title against the expected one.

[CatarinaGamboa]

Hi @subha0319! Thanks for contributing! Can you add a couple of examples with those annotations to see if it is working? We can also decide to have those annotation lines as the first line in the file, so that it is easier to check it and faster to run the tests

[subha0319]

Hi @CatarinaGamboa, Thanks for the feedback.

I've added the ExpectedError annotation to a couple more test files as you suggested: ErrorAfterIf.java and ErrorArithmeticBinaryOperations.java (along with ErrorSimpleAssignment.java which I had updated earlier).

And I've made sure to place the annotations on line 1 in all the examples.

Let me know if there's anything else.

[CatarinaGamboa]

left some comments, we can change the getExpectedError to be more eddicient

[subha0319]

Hi @CatarinaGamboa,

Thanks for the great review! I've updated the PR with all your suggestions:

• I've changed the logic to use a .contains() check, so the error tags can be more general and robust (e.g., // @ExpectedError: "Type expected"). I've updated the example files to use these general tags.

• I've refactored the getExpectedError method to return an Optional instead of null, which is much cleaner.

• Since we agreed the tag should be on the first line, I've also changed the file reader to only check the first line using findFirst().

Let me know if there's anything else!