Fix: Redirect users to login page from invite link (when signed out)

From a user:

I clicked Accept invite in this email but then it took me to https://macroapp.io/signup/new. If I try to enter my email address to sign up it says I already have an account. I was expecting when I clicked accept invite to be allowed to sign in

To improve this we can have two variants of the new workspace email:

You have been invited to a workspace -> create account
You’ve been added to a workspace -> view workspace