Is your feature request related to a problem? Please describe.

Currently, ORY Hydra validates the configuration in a very crude way. We should fix that and support JSON Schema as we already do in Oathkeeper and Kratos.

To see how kratos does that (validation and reloading), check here: https://github.com/ory/kratos/blob/master/cmd/serve.go#L53

Describe the solution you'd like

Hydra already implements the architecture of kratos/oathkeeper that supports hot reloading of config values. Some config values (such as the server bind address) can not be reloaded and should thus cause an error (see how kratos/oathkeeper is handling that). We need to create a list of variables that can not be reloaded. I believe that the fosite's config doesn't support reloading at this time because many config values are read only once: