[P2] Support Java Wrapper Class natively

[felix021]

As optional keyword is not applicable to function arguments/response, Kitex will always generate non-pointer basic types, which makes it incompatible with Java methods defined with wrapper classes (such as Integer) as its arguments/response.

To improve the compatibility, we can define java wrapper classes in java.thrift and implement them as type aliases to the corresponding basic types in github.com/kitex-contrib/codec-dubbo/tree/main/java, which will be "recogonized" as struct types by Kitex and present in their pointer form in the generated code.

Before implemented, the quickest workaround is to add another method in the java server as an adaptor.