Create flag for reusing bubbled tasks

Flag: com.android.wm.shell.only_reuse_bubbled_task_when_launched_from_bubble
Test: NONE - adding flag
Bug: 328229865
Change-Id: I9f1a067786986b9b4f8c681da481546afa97c288

libs/WindowManager/Shell/aconfig/multitasking.aconfig

+# proto-file: build/make/tools/aconfig/aconfig_protos/protos/aconfig.proto
+
 package: "com.android.wm.shell"
 container: "system"
 
@@ -99,3 +101,13 @@ flag {
     description: "Enable UI affordances to put other content into a bubble"
     bug: "342245211"
 }
+
+flag {
+    name: "only_reuse_bubbled_task_when_launched_from_bubble"
+    namespace: "multitasking"
+    description: "Allow reusing bubbled tasks for new activities only when launching from bubbles"
+    bug: "328229865"
+    metadata {
+        purpose: PURPOSE_BUGFIX
+    }
+}