[Bug]: http-client-java, support Client / SubClient in different package

[weidongxu-microsoft]

Describe the bug

https://github.com/allenjzhang/typespec-e2e-demo/blob/cd13f41abb54bb86f80eeabfdefb1e48e3e59321/todoApp/spec/main.tsp

There is nested namespace that contains operations.
It would result in Client / SubClient in a different Java package.

Currently the Client in Java is initialized via package private constructor, hence the Client and SubClient be in same package.

Reproduction

https://github.com/allenjzhang/typespec-e2e-demo/blob/cd13f41abb54bb86f80eeabfdefb1e48e3e59321/todoApp/spec/main.tsp

Checklist

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• The provided reproduction is a minimal reproducible example of the bug.