[Ingest Manager] Replace OutputType enum with separate type and runti…

…me object (#82230)

## Summary

Expands on pattern added in #82188

### rutime value is now `outputType.Elasticsearch` (lowercase b/c JS value)

```diff
-  type: OutputType.Elasticsearch,
+  type: outputType.Elasticsearch,
```

<img width="821" alt="Screen Shot 2020-11-02 at 4 46 24 PM" src="https://user-images.githubusercontent.com/57655/97923244-ae4ccc80-1d2b-11eb-9cc9-d98636ca9a40.png">
<img width="594" alt="Screen Shot 2020-11-02 at 4 46 35 PM" src="https://user-images.githubusercontent.com/57655/97923245-aee56300-1d2b-11eb-917e-483a68280e8e.png">
<img width="429" alt="Screen Shot 2020-11-02 at 4 46 47 PM" src="https://user-images.githubusercontent.com/57655/97923246-aee56300-1d2b-11eb-964a-37b496211167.png">

### TS type is `OutputType`
#### Can get union type of values with `ValueOf<OutputType>`
<img width="455" alt="Screen Shot 2020-11-02 at 4 47 31 PM" src="https://user-images.githubusercontent.com/57655/97923247-aee56300-1d2b-11eb-8492-40a9367ad90e.png">

#### Or access as `OutputType['Elasticsearch']`

x-pack/plugins/ingest_manager/common/constants/output.ts

@@ -3,13 +3,17 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-import { OutputType } from '../types';
+import { NewOutput } from '../types';
 
 export const OUTPUT_SAVED_OBJECT_TYPE = 'ingest-outputs';
 
-export const DEFAULT_OUTPUT = {
+export const outputType = {
+  Elasticsearch: 'elasticsearch',
+} as const;
+
+export const DEFAULT_OUTPUT: NewOutput = {
   name: 'default',
   is_default: true,
-  type: OutputType.Elasticsearch,
+  type: outputType.Elasticsearch,
   hosts: [''],
 };

x-pack/plugins/ingest_manager/common/types/models/output.ts

@@ -4,14 +4,15 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-export enum OutputType {
-  Elasticsearch = 'elasticsearch',
-}
+import { outputType } from '../../constants';
+import type { ValueOf } from '../index';
+
+export type OutputType = typeof outputType;
 
 export interface NewOutput {
   is_default: boolean;
   name: string;
-  type: OutputType;
+  type: ValueOf<OutputType>;
   hosts?: string[];
   ca_sha256?: string;
   api_key?: string;

x-pack/plugins/ingest_manager/server/services/agents/checkin/state_new_actions.test.ts

@@ -10,7 +10,8 @@ import {
   createNewActionsSharedObservable,
 } from './state_new_actions';
 import { getNewActionsSince } from '../actions';
-import { OutputType, Agent, AgentAction, AgentPolicyAction } from '../../../types';
+import { Agent, AgentAction, AgentPolicyAction } from '../../../types';
+import { outputType } from '../../../../common/constants';
 
 jest.mock('../../app_context', () => ({
   appContextService: {
@@ -128,7 +129,7 @@ describe('test agent checkin new action services', () => {
           id: 'policy1',
           outputs: {
             default: {
-              type: OutputType.Elasticsearch,
+              type: outputType.Elasticsearch,
               hosts: [],
               ca_sha256: undefined,
               api_key: undefined,

x-pack/plugins/ingest_manager/server/types/models/output.ts

@@ -4,14 +4,11 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 import { schema } from '@kbn/config-schema';
-
-export enum OutputType {
-  Elasticsearch = 'elasticsearch',
-}
+import { outputType } from '../../../common/constants';
 
 const OutputBaseSchema = {
   name: schema.string(),
-  type: schema.oneOf([schema.literal(OutputType.Elasticsearch)]),
+  type: schema.oneOf([schema.literal(outputType.Elasticsearch)]),
   hosts: schema.maybe(schema.arrayOf(schema.string())),
   api_key: schema.maybe(schema.string()),
   fleet_enroll_username: schema.maybe(schema.string()),