Refactor channel remapping out of LogReader

This change takes all the logic to rename and remap channels in
LogReader and places it in a new class: ConfigRemapper. LogReader still
retains the same remapping/renaming API for backwards compatibility, but
now the args are basically just passed along to ConfigRemapper. This was
done to allow configs to be remapped without a corresponding log file.

Change-Id: Ia32d8a3e640e94af0b52397ccd322149588d6da4
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/events/logging/realtime_replay_test.cc b/aos/events/logging/realtime_replay_test.cc
index 8c7751e..4118550 100644
--- a/aos/events/logging/realtime_replay_test.cc
+++ b/aos/events/logging/realtime_replay_test.cc
@@ -363,7 +363,7 @@
                    &config_.message(), &replay_channels);
   EXPECT_DEATH(
       reader.RemapLoggedChannel<aos::examples::Ping>("/fake", "/original"),
-      "which is not included in the replay channels passed to LogReader");
+      "which is not included in the replay channels passed to");
 }
 
 }  // namespace aos::logger::testing