[Fix] CS-Rule: No external library in public API

[mssfang]

A fix to No External Dependency check style rule. Previously, it fails only on the method's return type but not parameter types, and not checking on a protected class.

Also, remove unused import

[alzimmermsft]

Does this check handle a scenario such as public void someMethod(Function<ByeBuf, OutputStream> aFunctionINeed)?

[vhvb1989]

minor things , open to talk about it 👍

[JonathanGiles]

Does this check handle a scenario such as public void someMethod(Function<ByeBuf, OutputStream> aFunctionINeed)?

Alan's point here is a good one. For example, ConfigurationClientCredentials has methods that take a Flux<ByteBuf> that should not be allowed. Please ensure that this is tested in this check too.

[JonathanGiles]

Looks good to me, after taking into account the feedback from the other reviewers.

[vhvb1989]

Looking great!

[mssfang]

Refactored the code and created a recursion method that takes care of (1) TYPE as a root node, it can have IDENT and/or TYPE_AURGUMENTS as children nodes; (2) TYPE_AURGUMENT as a root node, it can have IDENT and/or TYPE_AURGUMENTS as children nodes; (3) TYPE_AURGUMENTS as a root node, it can have TYPE_AURGUMENT as child node.