Fix qualified name for nested type
For interface, there are various "class names": Bn, Bp, I, ...
Nested types are declared in "I-" (ClassNames::INTERFACE) class of
parent type when the parent type is "interface".
Bug: 285373289
Test: m aidl-test-interface-{cpp,ndk,rust,java}
Test: atest aidl_unittests aidl_integration_test
Change-Id: I1f2cdf2cbfd0e2c49acfaeca5c571ce349166e11
Documentation for this project is currently maintained here:
https://source.android.com/devices/architecture/aidl/overview