Upgrade Swagger 2.0 to Open API Specification 3.0

[nazarhussain]

Expected behavior

The latest version of swagger is renamed to OAS3. It have plenty of improvements that we can utilized. Specially the multi server definition.

Actual behavior

We are using Swagger 2.0 currently. Which is kind of near to obsolete.

Steps to Develop

1. We are using swagger-node-runner which does not support OAS3
2. Either we fork and upgrade swagger-node-runner to support OAS3
3. Or instead the package sway package directory, which is the dependency of swagger-node-runner right now.
4. Upgrade the swagger specification we currently have in swagger.yml
5. Update the functional tests (if any change made in endpoints)

Which version(s) does this affect? (Environment, OS, etc...)

1.0.0

[nazarhussain]

@MaciejBaj An underlaying core library still don't support OAS3. So we should wait a bit further to see if its updated, then we will port our APIs.

apigee-127/sway#128 (comment)

[nazarhussain]

Un-assigning from myself. We will revisit this issue in coming releases and then assign available resource.

[shuse2]

Closing this in favor of #5213 , we will not use swagger runner , but the swagger.yaml will be used for documentation purpose.