Defer complex object creation until used by tests.

As part of supporting SysUI multivalentTests under the new Ravenwood
testing environment, tests need to be more careful about only
creating and interacting with "complex" objects when they're actually
needed by a test.  Attempting interactions during <init> or <clinit>
of the overall test class fails on Ravenwood when these complex
objects aren't yet supported, and they throw an exception.

The smoothest path towards mitigating this is by leveraging the
`by lazy` feature of Kotlin, where we only create and interact with
a complex object when actually requested by test method code.  This
strategy gives Ravenwood enough room to successfully instantiate
test classes to decide if it should be executed or ignored via
future annotations.

This change is a purely mechanical adding of `by lazy` in all
relevant locations, as uncovered via local investigation.

Bug: 319647875
Test: atest SystemUiRoboTests
Change-Id: I16b62d790511a9b9f37491f2e0d0f4719783d2ac