The AIDL compiler now uses SourceProvider to compiler the generated Rust
code from system/tools/aidl/build/aidl_interface.go using its own
SourceProvider object, which needs access to baseSourceProvider and all
methods of SourceProvider.
Test: mmma system/tools/aidl with 1357705 applied
Change-Id: I226609a7fccca2e7e1bfbad5d69d1821d37e43a1