Feature/implement med halt tests for robust model evaluation

[chakravarthik27]

This pull request introduces several new classes and methods for transforming and running clinical and robustness tests. The changes primarily involve adding new classes for different types of tests and incorporating utility functions to handle question-answering prompts.

New Classes and Methods:

• Added FCT and NOTA classes for clinical tests with methods for transforming and running tests on sample lists. (langtest/transform/clinical.py)
• Introduced FCT, NOTA, and FQT classes for robustness tests, each with a transform method to modify sample lists. (langtest/transform/robustness.py)

Utility Functions:

• Imported build_qa_input and build_qa_prompt functions to assist in constructing question-answering prompts. (langtest/transform/clinical.py)