Refactor call audio routing and bluetooth management.

app/src/main/java/org/thoughtcrime/securesms/util/ContextExtensions.kt

@@ -0,0 +1,15 @@
+package org.thoughtcrime.securesms.util
+
+import android.content.BroadcastReceiver
+import android.content.Context
+
+fun Context.safeUnregisterReceiver(receiver: BroadcastReceiver?) {
+  if (receiver == null) {
+    return
+  }
+
+  try {
+    unregisterReceiver(receiver)
+  } catch (e: IllegalArgumentException) {
+  }
+}