ProfileActivity: Refactor into clean layers of functionality

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/ServiceConnectionProvider.java

@@ -0,0 +1,13 @@
+package com.wireguard.android;
+
+/**
+ * Interface for activities that provide a connection to a service.
+ */
+
+interface ServiceConnectionProvider<T> {
+    void addServiceConnectionListener(ServiceConnectionListener<T> listener);
+
+    T getService();
+
+    void removeServiceConnectionListener(ServiceConnectionListener<T> listener);
+}