Allow setSettings/setGlobalSettings to accept updater callbacks

[fhollermayer]

This change extends the existing functionality of Action.setSettings and settings.setGlobalSettings by adding overloads that accept a callback function instead of a static object. The callback receives the current settings and returns the updated settings, allowing updates to be expressed relative to the existing state. As a result, these setter functions can be used without explicitly calling the corresponding retrieval methods.

settings.setGlobalSettings(v => ({
  ...v,
  foobar: "123",
}));

or

action.setSettings(v => {
  v.foobar = "123";
  return v;
});

This PR is intended as a compilable proposal rather than a change request—feel free to discard it if it’s not a good fit.