chore: add echo helper to create an agent with token (#6576)

This should reduce some LOC and duplication in tests!

cli/configssh_test.go

@@ -94,23 +94,7 @@ func TestConfigSSH(t *testing.T) {
 				},
 			},
 		}},
-		ProvisionApply: []*proto.Provision_Response{{
-			Type: &proto.Provision_Response_Complete{
-				Complete: &proto.Provision_Complete{
-					Resources: []*proto.Resource{{
-						Name: "example",
-						Type: "aws_instance",
-						Agents: []*proto.Agent{{
-							Id:   uuid.NewString(),
-							Name: "example",
-							Auth: &proto.Agent_Token{
-								Token: authToken,
-							},
-						}},
-					}},
-				},
-			},
-		}},
+		ProvisionApply: echo.ProvisionApplyWithAgent(authToken),
 	})
 	coderdtest.AwaitTemplateVersionJob(t, client, version.ID)
 	template := coderdtest.CreateTemplate(t, client, user.OrganizationID, version.ID)