[HostStubGen] Support ignore policy on more methods

Ignore policy used to only support methods that return void. Let's
extend support to all types, and return each type's default value.
Calling ignored methods will not crash and result in no-op at runtime,
however these methods are not considered as "supported".

Also add ignore support to text policy, and text policy only, as
annotations are reserved for supported classes.

Flag: EXEMPT host side test change only
Bug: 292141694
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Change-Id: Ida3e939b26e1a637b0a54f8e88fd6202ab0502c2