Improved AutofillManager and Activity dump() methods:

- Print compatibility mode info and activity token on AutofillManager.dump().
- Add --autofill option on Activity so it just dump autofill state.

Also fixed checkstyle import warnings on ActivityManagerShellCommand.

Bug: 112417431
Bug: 112584717

Test: adb shell dumpsys activity top --autofill

Change-Id: Id56b56a5d7e591d5204663a1da1322a15f8ef3aa