[test] add a new test for LLM class

[skcoirz]

• added unit test cases for LLM base class.
• covering both realtime and async entry points.

[dev2049]

what the use case? don't we already have fake llms

[skcoirz]

what the use case? don't we already have fake llms

this is just a simple one time class, being used in this test case only. The difference is the call function. This class here simply returns the prompt. Fake LLM class requires several more steps for a similar result. There is no major difference. Using this simple class here makes the test logics much simpler.

This test case is added for LLM Class generation and ageneration functions.

cc @dev2049

[baskaryan]

stale