Allow ActivityEmbedding in APEX modules.

Also this lib uses HTTP and doesn't declare it, so after manifest merge
the APEX module won't build.  Add the uses-library.

Bug: 253394518
Test: test builds
Change-Id: I94cb2be58d88521ed10e4fba5b5e11169bead624
diff --git a/packages/SettingsLib/ActivityEmbedding/Android.bp b/packages/SettingsLib/ActivityEmbedding/Android.bp
index 332bebf..c35fb3b 100644
--- a/packages/SettingsLib/ActivityEmbedding/Android.bp
+++ b/packages/SettingsLib/ActivityEmbedding/Android.bp
@@ -26,4 +26,9 @@
         "androidx.window.extensions",
         "androidx.window.sidecar",
     ],
+
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.permission",
+    ],
 }