Add aconfig flag to guard contextual tips features.

Bug: 322891421
Test: NONE this just adds the flags. No change in behavior.
Flag: ACONFIG com.android.systemui.enable_contextual_tips DEVELOPMENT
Change-Id: I809aac8880fc0432f5b3687842c5c77b38a5e451
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index ba3026e..6e4a4ea 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -389,6 +389,13 @@
 }
 
 flag {
+   name: "enable_contextual_tips"
+   description: "Enables showing contextual tips."
+   namespace: "systemui"
+   bug: "322891421"
+}
+
+flag {
    name: "shaderlib_loading_effect_refactor"
    namespace: "systemui"
    description: "Extend shader library to provide the common loading effects."