Add ids to flatbuffer fields in y2012, y2016, frc971, and aos

Change-Id: I9ed9006ce6224e2df0459df47771786b928164a1
diff --git a/frc971/codelab/basic_output.fbs b/frc971/codelab/basic_output.fbs
index 7f3b0b9..be27122 100644
--- a/frc971/codelab/basic_output.fbs
+++ b/frc971/codelab/basic_output.fbs
@@ -5,7 +5,7 @@
   // hope to intake something. Voltages on our robots generally range from
   // -12.0 V to +12.0V. In this case, the intake should be commanded to actually
   // intake by setting the voltage to 12 V.
-  intake_voltage:double;
+  intake_voltage:double (id: 0);
 }
 
 root_type Output;