Add UserData to store user related information

This is a preparation CL for changing IMMS to store
InputBindingController per user.

This is a refactoring CL, no regression is expected.

Bug: 325515685
Test: atest CtsInputMethodTestCases FrameworksServicesTests

Change-Id: I20ba680a8755df794e477502f85ee0d970b709fb
4 files changed