Move SystemUI test utils to SystemUI/tests/utils/ (1/2)

This CL moves all the SystemUI-test-utils files to a separate
SystemUI/tests/utils/ directory. This paves the way towards making this
filegroup a reusable library instead.

The files have been move using a small bash script [1].

[1] https://paste.googleplex.com/5565628199993344

Bug: 240431193
Test: m SystemUI-tests SystemUIGoogleTests SystemUIGoogleScreenshotTests ArcSystemUI-test
Change-Id: I43ff578be211f1ef3f9c5bffd5c65771ef1492dc