Allow omitting the token in the parameters of $apolloHelpers.onLogin

[Tinoooo]

What problem does this feature solve?

In case the authentication is done via a HttpOnly cookie, there is no need to store the token in a seperate cookie. A current workaround is passing a dummy token.

What does the proposed changes look like?

It should be possible to call $apolloHelpers.onLogin without the first parameter (the token).

_{This feature request is available on Nuxt community (#c309)}