Add a replaceSession function to ovewrite the session data instead merging it.

[remonke]

Describe the feature

If I want to use discrimated unions for session types in my app, I currently have to do this:

type AppSessionData =
  | {
      type: undefined;
    }
  | {
      type: 'pending-oauth';
      payload: {
        provider: AppOauthProvider;
        providerId: string;
      };
    }
  | {
      type: 'active';
      payload: {
        id: number;
        userId: number;
      };
    };

Honestly, I'm not a big fan of this approach.
I think it would nice if there was a function like replaceSession to simply assign a new object to session.data instead of doing Object.assign.

Additional information

• Would you be willing to help implement this feature?

[remonke]

Okay I can simply use a different session name for this.

Sorry for being so retarded.