Add support for authentication methods defined in OpenAPI schema

OpenAPI specifications can contain information on how to authenticate with the API. We should add support for helping users out with authenticating using those methods.
E.g.
```ts
const anonymousClient = createMyApiClient("")
const authClient = createMyApiClient("", {
  authentication: {
    type: "basic",
    username: "johnny99",
    password: "bruuuuce"
  }
})
```