Update SystemUI aconfig files to match new style

See go/sysui-aconfig-structure

Bug: 297872375
Test: build
Change-Id: Ide9ec71e572195d69f2e1995bd140b41f21e4041
diff --git a/packages/SystemUI/aconfig/accessibility.aconfig b/packages/SystemUI/aconfig/accessibility.aconfig
new file mode 100644
index 0000000..8841967
--- /dev/null
+++ b/packages/SystemUI/aconfig/accessibility.aconfig
@@ -0,0 +1,8 @@
+package: "com.android.systemui"
+
+flag {
+    name: "floating_menu_overlaps_nav_bars_flag"
+    namespace: "accessibility"
+    description: "Adjusts bounds to allow the floating menu to render on top of navigation bars."
+    bug: "283768342"
+}