HostStubGen: Support "ignore" annotation.

- Also support suffix matching in annotation-allowed-classes
- Also make the prefix / suffix match stricter

This is needed for aconfig flag support.

Flag: EXEMPT host test change only
Bug: 292141694
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh

Change-Id: I588c0602bfe1fc375fe6de2871fcd8b9e02c3b27