Check size limits on metadata and name set from client. (#2850)

* Send error response when update metadata fails.

Keeping it simple for the first implementation.
- Send error response only if request_id != 0
- Two kinds of errors notified
  o does not have permissions - NOT_ALLOWED
  o attributes exceeds size limits -  INVALID_ARGUMENT

* Check size limits on metadata and name set from client.

Added a name length limit also.

* check name length in service update participant path also

* limit check in limit config

* update protocol

* longer keys

test/integration_helpers.go

@@ -40,7 +40,7 @@ import (
 
 const (
 	testApiKey        = "apikey"
-	testApiSecret     = "apiSecret"
+	testApiSecret     = "apiSecretExtendTo32BytesAsThatIsMinimum"
 	testRoom          = "mytestroom"
 	defaultServerPort = 7880
 	secondServerPort  = 8880