[FEATURE] UX: handle tool misconfiguration better

[langchain4j]

In the following case, when tools is a class, not an object, we should do a better job handling this situation.

AiServices.builder(Assistant.class)
                .tools(Tools.class)
                .build();

Exception should be thrown if (one of) the provided object(s) is a Class.

[anunnakian]

If we try to create an object when we have a Class as a parameter. Do we have to handle the following case too ?

AiServices.builder(Assistant.class)
                .tools(Tools.class, tools2, tools3)
                .build();

[langchain4j]

@anunnakian after a second thought, I am not sure it is a good idea to introduce another reflexion usage, I would rather just throw an exception if the provided object is a Class

[anunnakian]

Got it! could you assign this issue to me, I'll make a PR at the end of the day