SysUI Tests: Make SysUI test self-test errors more expressive

When AAAPlusPlusVerifySysuiRequiredTestPropertiesTest failed, you had to go look
in logcat for why that was. Instead, we're now putting the sub-errors in the
assertion itself such that when it fails it prints them all.

Test: add a test without the sysui base classes and without size; atest AAAPlusPlusVerifySysuiRequiredTestPropertiesTest
Change-Id: I75ba9ec6785beb044ffd08160030e99f5155a234