Add clipboard indication text view

Fork system toast layout to show indication under clipboard overlay and
allow override to provide different indication text.

Bug: 361199935
Flag: com.android.systemui.show_clipboard_indication
Test: atest ClipboardOverlayControllerTest
Change-Id: I6e38d386e94fdbcbaf4101676aec6abdead2c3bb
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 5c5edb1..b2ea6aa 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -1559,6 +1559,13 @@
 }
 
 flag {
+   name: "show_clipboard_indication"
+   namespace: "systemui"
+   description: "Show indication text under the clipboard overlay when copied something"
+   bug: "361199935"
+}
+
+flag {
    name: "media_projection_dialog_behind_lockscreen"
    namespace: "systemui"
    description: "Ensure MediaProjection Dialog appears behind the lockscreen"