Improve error message if not full token is not copied (Checksum correct)

<img width="893" alt="image" src="https://github.com/getsentry/sentry-cli/assets/363802/577758ca-263e-4028-9048-a991514cdea5">

If you fail to copy the full token - we should improve the error message to tell users they fucked up copying the full token (because checksum check failed)