rpk: add err message of CreateACL response

Response of CreateACL contains an ErrMessage field
that can provide more information about unknown
failures.

src/go/rpk/pkg/cli/security/acl/create.go

@@ -69,6 +69,10 @@ Allow write permissions to user buzz to transactional ID "txn":
 			tw := out.NewTable(headersWithError...)
 			defer tw.Flush()
 			for _, c := range results {
+				errMsg := kafka.ErrMessage(c.Err)
+				if c.ErrMessage != "" {
+					errMsg = fmt.Sprintf("%v: %v", errMsg, c.ErrMessage)
+				}
 				tw.PrintStructFields(aclWithMessage{
 					c.Principal,
 					c.Host,
@@ -77,7 +81,7 @@ Allow write permissions to user buzz to transactional ID "txn":
 					c.Pattern,
 					c.Operation,
 					c.Permission,
-					kafka.ErrMessage(c.Err),
+					errMsg,
 				})
 			}
 		},

tests/rptest/tests/acls_test.py

@@ -307,7 +307,8 @@ def test_invalid_acl_topic_name(self):
 
         acl = [acl for acl in acls if acl.resource_name == resource]
         assert len(acl) == 1, f'Expected match for {resource} not found'
-        assert acl[0].error == 'INVALID_REQUEST'
+        assert 'INVALID_REQUEST' in acl[
+            0].error, f'expected INVALID_REQUEST to be in {acl[0].error}'
 
     '''
     The old config style has use_sasl at the top level, which enables