Add sysWhitelistedAppsExceptIdle in whitelist

Add sysWhitelistedAppsExceptIdle to PowerWhitelistBackend so we
can get doze whitelist except idle. Now this list is used in
anomaly detection in settings.

Bug: 74241534
Test: RunSettingsLibRoboTests
Change-Id: I42619cbc9fe29f33f83fbd1517017db6016e3674