moving the voice message limit to the config module

vector-config/src/main/java/im/vector/app/config/Config.kt

@@ -37,6 +37,11 @@ object Config {
      */
     const val ALLOW_EXTERNAL_UNIFIED_PUSH_DISTRIBUTORS = true
 
+    /**
+     * The maximum length of voice messages in milliseconds.
+     */
+    const val VOICE_MESSAGE_LIMIT = 120_000L
+
     /**
      * The analytics configuration to use for the Debug build type.
      * Can be disabled by providing Analytics.Disabled