Define core server types and interfaces

[jbearer]

• TideDisco<State, Error: net::Error + Into<tide::Error>> (should we call it something more descriptive like App or Server?)
  • new(state: State) -> Self
  • register_module<ModuleError: Into<Error>>(&mut self, base_url: Url, api: ApiSpec<State, ModuleError>) -> &mut Self
  • serve(self) -> JoinHandle<Result<()>>
• ApiSpec<State, Error>
  • new(api: toml::Value) -> Result<Self>
  • route<T: Serialize>(&mut self, name: &str, handler: impl Fn(RequestParams<State>) -> Result<T, Error>) -> &mut Self
  • private register(self, app: &mut tide::App)
• RequestParams<State>
  • state(&self) -> &State
  • param(&self, name: &str) -> Result<&UrlParam>