Fix DefaultAndroidManifest embedded-resource name with explicit LogicalName

Summary: ManifestMod.CreateDefaultAndroidManifest loads the bundled default Android manifest as an embedded resource via GetManifestResourceStream("Facebook.Unity.Editor.android.DefaultAndroidManifest.xml"). The .csproj declared <EmbeddedResource Include="android\DefaultAndroidManifest.xml" /> with no explicit LogicalName, leaving the resource’s manifest name up to the build toolchain. Under mono’s msbuild (used for both local mac builds and the Skycastle CI), the android folder segment is dropped, so the resource is embedded as Facebook.Unity.Editor.DefaultAndroidManifest.xml. That name mismatch makes GetManifestResourceStream return null, and the subsequent XmlDocument.Load(null) throws a NullReferenceException inside FacebookBuild.ExportPackage‘s manifest-generation step, failing the .unitypackage export.

Add an explicit <LogicalName> so the resource is always named exactly what the code requests, independent of the toolchain’s resource-naming convention.

---

Differential Revision: D109900918

fbshipit-source-id: 8118aaca486f517818867f979a8d6f07ed3a6f7b