Add tests for window decor caption and fix a flaky test

We introduced display windowing mode and freeform policy to our decor
view handling. The tests are unit tests to make sure the
WindowConfiguration has the correct return value of
hasWindowDecorCaption with the new conditions.

The WindowConfigurationTests was flaky because the AppBounds root
configuration now should consider the cutout and the test expected
result doesn't. This patch also fixed it.

Test: atest WindowConfigurationTests
Bug: 123425316
Bug: 74078662
Change-Id: I5c7f4484b240f9a2bf9d18e9414b8201dc4c0ec3