Add baggage propagator (#308)

*Description of changes:* 

Adding baggage propagator to be consistent with Javascript
Instrumentation


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Author: liustve

lambda-layer/src/otel-instrument

@@ -95,7 +95,7 @@ fi
 export LAMBDA_RESOURCE_ATTRIBUTES="cloud.region=$AWS_REGION,cloud.provider=aws,faas.name=$AWS_LAMBDA_FUNCTION_NAME,faas.version=$AWS_LAMBDA_FUNCTION_VERSION,faas.instance=$AWS_LAMBDA_LOG_STREAM_NAME,aws.log.group.names=$AWS_LAMBDA_LOG_GROUP_NAME";
 
 if [ -z ${OTEL_PROPAGATORS} ]; then
-    export OTEL_PROPAGATORS="xray,tracecontext,b3,b3multi"
+    export OTEL_PROPAGATORS="xray,tracecontext,baggage,b3,b3multi"
 fi
 
 if [ -z "${OTEL_AWS_APPLICATION_SIGNALS_ENABLED}" ]; then