Add JSON Schema files & Swagger endpoint

[jfsiii]

refs #40034

Summary

Even this description is WIP

• Add request validation (refs [EPM] Validate request parameters #38582) via naive Joi spec
• Add response validation via Joi spec generated from JSON Schema
• Add swagger endpoint to describe API endpoint

Notes

JSON Schema

JSON Schema for the two routes manager consumes from the registry. Generated from actual data on the registry, but can be edited by hand to make more accurate. Save the schemas to schemas/consumed directory.

npx quicktype -t IntegrationList --lang schema -o schemas/consumed/list.schema.json http://integrations-registry.app.elstc.co/list
npx quicktype -t Package --lang schema -o schemas/consumed/package.schema.json http://integrations-registry.app.elstc.co/package/docker-1.2.3 

Manager can generate / maintain these or get published from elsewhere (e.g. registry).

Swagger

gist of swagger.json output
Can feed that file to an online viewer like this one or we could install one. For now, just having the file is a big win

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[jfsiii]

Closing this PR isn't useful any longer. More specifically, we've moved away from the Hapi ecosystem dependencies this uses.

We did add a spec file in #68323 & the registry has a ticket for discussing OpenAPI elastic/package-registry#487