Equivalent of getToken for generating JWT based on custom template

[rolandtolnay]

Use case

After some back-and-forth debugging the example app, and creating a fork that merges in the favicon fixes, I managed to generate a token for our organization using the SDK.

This was passed back to us using the FutureOr<void> write<T>(String key, T value) persistor methods.

The token however doesn't follow the JWT template that we are looking for.
Other platform SDK's expose a getToken() method which allows passing in a custom template name and returns a token in that format.

Proposal

Spent some time searching the project for similar functionality, with no luck.

What would be your suggested approach for generating a JWT token with the Flutter SDK that follows one of our custom templates?

We need this to be able to authenticate correctly with our backend API's.