[Feature]: Implement Integration Test for OpenApi tools

[kpanot]

Context

As a developer, I would expect to have IT to ensure that the OpenAPI tools are not broken on code and dependency update.

Proposal

The Integration Tests should be based on the repository generated by @ama-openapi/create and cover, at least, the following cases:

• should not break when no manifest is present
• should break when invalid manifest is present
• should correctly reference a model (when no transform)
• should correctly generate a transformed model
• should modify dependency transformed model $ref to continue targeting the original file
• should properly handle version conflict to a 3rd dependency

All these usecases should result to a valid redocly bundle execution.