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

This should reduce some LOC and duplication in tests!

cli/agent_test.go

@@ -31,24 +31,8 @@ func TestWorkspaceAgent(t *testing.T) {
 		})
 		user := coderdtest.CreateFirstUser(t, client)
 		version := coderdtest.CreateTemplateVersion(t, client, user.OrganizationID, &echo.Responses{
-			Parse: echo.ParseComplete,
-			ProvisionApply: []*proto.Provision_Response{{
-				Type: &proto.Provision_Response_Complete{
-					Complete: &proto.Provision_Complete{
-						Resources: []*proto.Resource{{
-							Name: "somename",
-							Type: "someinstance",
-							Agents: []*proto.Agent{{
-								Id:   uuid.NewString(),
-								Name: "someagent",
-								Auth: &proto.Agent_Token{
-									Token: authToken,
-								},
-							}},
-						}},
-					},
-				},
-			}},
+			Parse:          echo.ParseComplete,
+			ProvisionApply: echo.ProvisionApplyWithAgent(authToken),
 		})
 		template := coderdtest.CreateTemplate(t, client, user.OrganizationID, version.ID)
 		coderdtest.AwaitTemplateVersionJob(t, client, version.ID)