Set Android client

This checks user-agent before X-OmnivoreClient so the more explicit
X-OmnivoreClient overrides the derived client being set from user
agent.

android/Omnivore/app/src/main/java/app/omnivore/omnivore/core/network/Networker.kt

@@ -17,5 +17,7 @@ class Networker @Inject constructor(
     private suspend fun authToken() = datastoreRepo.getString(omnivoreAuthToken) ?: ""
 
     suspend fun authenticatedApolloClient() = ApolloClient.Builder().serverUrl(serverUrl())
-        .addHttpHeader("Authorization", value = authToken()).build()
+        .addHttpHeader("Authorization", value = authToken())
+        .addHttpHeader("X-OmnivoreClient", value = "android")
+        .build()
 }