Add platform/system/connectivity/apmanager to the manifest

BUG=23593224

default.xml

@@ -497,6 +497,7 @@
   <project path="prebuilts/tools" name="platform/prebuilts/tools" groups="pdk,tools" />
   <project path="sdk" name="platform/sdk" groups="pdk-cw-fs,pdk-fs" />
   <project path="system/bt" name="platform/system/bt" groups="pdk" />
+  <project path="system/connectivity/apmanager" name="platform/system/connectivity/apmanager" />
   <project path="system/connectivity/shill" name="platform/system/connectivity/shill" />
   <project path="system/core" name="platform/system/core" groups="pdk" />
   <project path="system/extras" name="platform/system/extras" groups="pdk" />