Drop our openapi-spec packages, use openapi3-ts instead

[bajtos]

https://github.com/metadevpro/openapi3-ts looks more feature complete than our own openapi packages. Should we use openapi3-ts instead?

If we want to support both Swagger v2 and OpenAPI v3 then we probably cannot drop our packages, unless there is a replacement available.

UPDATE:

Looks like we have already dropped most of our custom type definitions. As of today (0411811aa), openapi-v3-spec-types provides only few helpers:

• OpenApiSpec as an alias for OpenAPIObject
• createEmptyApiSpec()
• isSchemaObject() and isReferenceObject() (type guards)

Acceptance criteria

• contribute type guards to openapi3-ts - see Add type guards for SchemaObject and ReferenceObject metadevpro/openapi3-ts#46 and Refactor openapi guards to use the upstream version #2974
• try to upstream createEmptyApiSpec, e.g. to src/dsl/OpenApiBuilder.ts
• move the rest to our openapi-v3 package (createEmptyApiSpec should go to openapi--spec-builder package) - see Remove usages of "@loopback/openapi-v3-types" and deprecate the package #3220
• and finally remove openapi-v3-types - see feat: remove openapi-v3-types package #3385

[bajtos]

Related: #182.

[dhmlau]

@jannyHou , with your openapiv3 work, is this ticket still valid?