Add user serial number to communal db schema

This change adds a new column to the communal database storing the
serial number of the user associated with each widget. It also
implements a migration that is run when a device is updated from the
previous version of database, populating the default value as -1.

Test: atest CommunalDatabaseMigrationsTest
Test: atest CommunalBackupHelperTest
Test: atest CommunalBackupUtilsTest
Test: atest CommunalWidgetDaoTest
Test: atest CommunalWidgetRepositoryImplTest
Bug: 330945203
Flag: com.android.systemui.communal_hub
Change-Id: I93c231ab9a25f580730628815e588e986ffd0102
diff --git a/packages/SystemUI/Android.bp b/packages/SystemUI/Android.bp
index 469b9ce..8e9f5d4 100644
--- a/packages/SystemUI/Android.bp
+++ b/packages/SystemUI/Android.bp
@@ -668,6 +668,7 @@
     ],
     asset_dirs: [
         "tests/goldens",
+        "schemas",
     ],
     static_libs: [
         "SystemUI-res",
@@ -707,6 +708,7 @@
         "androidx-constraintlayout_constraintlayout",
         "androidx.exifinterface_exifinterface",
         "androidx.room_room-runtime",
+        "androidx.room_room-testing",
         "androidx.room_room-ktx",
         "device_state_flags_lib",
         "kotlinx-coroutines-android",