Gradle AAR repository directories with $S(PluginDir) are relative instead of absolute path

Gradle AAR import paths need to be absolute instead of relative since the current work directory used to package Gradle is not the same as Ant.

1. Create project
2. Enable Gradle in Android project settings
3. Edit GearVR_UPL.xml and add:

<AARImports>
<insertValue value="repositories $S(PluginDir)/../../Source/ThirdParty/AndroidRepository"/>
<insertNewline/>
</AARImports>

4. make an empty Engine/Plugins/Runtime/Oculus/OculusVR/Source/ThirdParty/AndroidRepository/m2repository directory
5. Package for Android
6. Check the contents of Intermediate/Android/APK/gradle/app/aar-imports.gradle and make sure all the maven

sections have absolute paths
7. remove the GearVR_UPL.xml change and delete the directories created for the test in step 4