Setup aconfig for communal

This change introduces an aconfig file for communal features, and adds a
first flag which controls the communal hub experience.

Bug: 304584416
Bug: 304585752
Test: verified by adding some local logging code which checks the
communal_hub flag. To turn on and off the flag, I ran: adb shell
device_config put communal com.android.systemui.communal.communal_hub
{true|false}

Change-Id: Ifd9e1f7ca6e103a37d888691a10c1f3d60b7e260
diff --git a/packages/SystemUI/aconfig/communal.aconfig b/packages/SystemUI/aconfig/communal.aconfig
new file mode 100644
index 0000000..8ecb984
--- /dev/null
+++ b/packages/SystemUI/aconfig/communal.aconfig
@@ -0,0 +1,8 @@
+package: "com.android.systemui.communal"
+
+flag {
+    name: "communal_hub"
+    namespace: "communal"
+    description: "Enables the communal hub experience"
+    bug: "304584416"
+}