Add flashlight dialog test tags

These were needed to be used for finding the flashlight title and done
button in the e2e tests.

Test: atest FlashlightDialogDelegateTest
Test: atest OpenFlashlightDialog
Bug: 422667361
Flag: com.android.systemui.flashlight_strength

Change-Id: Ibc6f384391683c4672b4510585bf2db00a8ffec5