Log communal widgets snapshot

COMMUNAL_HUB_SNAPSHOT is a pulled atom which requires registering a
callback which gets called daily to log the current state of the widgets
in the Glanceable Hub, which includes first party widgets component
names, and total widget count.

Test: statsd_testdrive 10226
Test: atest CommunalMetricsLoggerTest
Test: atest CommunalMetricsStartableTest
Bug: 318712030
Flag: com.android.systemui.communal_hub
Change-Id: I1010b8b479e5115bccd8bdfd737488840e9a06c7