[EPM] Use NP server route handler

[jfsiii]

Edit: Don't work on this until #44170 #44174 server.route from #44620, and #44143 is resolved

Swap hapi implementation out for NP. Letters added to make it easy to refer to, not because the order matters.

• A: Update the way route handlers are added [Discuss] Add NP core.http.route #44174 Introduce HttpApi and HttpResource services #44620

• B: Update the way routes are validated NP Router handler doesn't provide to request body on validate: false #44170 (comment)

• C: Change handlers to get Elasticsearch and Saved Object clients from context

• D: Change the signature for handlers ((req, context) => (context, req, res))

• E: Handle response status, headers (response.notFound, response.ok, etc)

From #41894

import { schema, TypeOf } from '@kbn/config-schema';
const router = httpSetup.createRouter();

router.get({
  path: 'path/{id}',
  validate: false // or see B
},
async (context, request, response) => {
  const data = await findObject(request.params.id);
  if (!data) return response.notFound();
  return response.ok({
    body: data,
    headers: {
      'content-type': 'application/json'
    }
  });
});

A: Avoid router.get, router.post, etc. in favor of server.route coming as part of #44620

B: We don't do options.query or options.params right now, but will need to update (remove) types in handlers and switch to @kbn/config-schema-based approach.

C: elasticsearch is available now under context.core.elasticsearch. @rudolf is [currently migrating the Saved Objects client](ES is ready. SO PR is #44143) and will also expose them under context.core.

D: related to B Blocked on C (getting ES & SO from context)

[elasticmachine]

Pinging @elastic/infra-logs-ui

[jfsiii]

Did a quick POC in jfsiii@6aab980 (see commit message for more info)

[sgrodzicki]

@jfsiii are you still investigating? What does the blocked label imply?

[jfsiii]

@sgrodzicki No, I'm not investigating it. blocked is that it's unable to be worked on until some other issues are resolved.

I didn't know how to classify it since it's neither Investigating nor Ready. Back to Backlog, perhaps?

[sgrodzicki]

Back to backlog sounds reasonable. Thanks for the clarification!

[ruflin]

@jfsiii With the recent changes and merge to master, can this be closed?

[jfsiii]

@ruflin yes. Just closed it