Annotation is printable

An AIDL annotation is now modeled using AidlAnnotation class instead of
the Annotation enum. And ToString() method is added to AidlAnnotatable
to print the annotations back in text form. This will be used when
printing API signature of AIDL files.

Bug: 110758635
Test: runtests.py

Change-Id: I6fa3f88ebd5e6c2a0f6374b4711d2b20b93220f2
3 files changed