refactor: move remaining api packages to core (#1731)

* core 1

* api/openai/files fix

* core 2 - core/config

* move over core api.go and tests to the start of core/http

* move over localai specific endpoints to core/http, begin the service/endpoint split there

* refactor big chunk on the plane

* refactor chunk 2 on plane, next step: port and modify changes to request.go

* easy fixes for request.go, major changes not done yet

* lintfix

* json tag lintfix?

* gitignore and .keep files

* strange fix attempt: rename the config dir?