Feature/http api new approach

[Jan-Schuppik]

Initial setup for the new approach of the http-api with openapi description.

Resolves:

• Add an HTTP API to configure contacts and contactgroups #176
• OpenAPI description for the contact and contactgroup API #345

require:

• Add column external_uuid to contact/contactgroup/channel table icinga-notifications#216
• Feature/notifications api icinga-php-thirdparty#58

[nilmerg]

This review covers only the early parts of routing and dispatching.

[nilmerg]

Oh, and I got the postgres tests working in my environment. Please get back to me for this.

[sukhwinder33445]

I have looked at channels and contact tests so far, next I will look at contactgroup tests.

[sukhwinder33445]

Please add following changes as well:

• The PHPDoc for the method must contain a newline between different annotations, i.e. @param, @return.
• Update method PHPDoc if required.
• Make the getPlural() method protected.
• Remove the resolved todos.

[nilmerg]

Let's discuss how we handle the openapi description and the usage of Swagger, as there are three possible solutions for me:

• Caching (properly, not the way it's right now ;) )
• CI (as your todo suggests)
• Static (it's a versioned api after all)

[nilmerg]

Missing license header. It seems, not only this file is missing it, please make sure all PHP files have one.

[nilmerg]

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