Integrate FortiToken Cloud to GitLab 2FA options

FortiToken Cloud is the SaaS version of FortiAuthenticator

Questions

Do we have access to a ruby SDK? we don't have a ruby SDK, but as shown here lib/gitlab/auth/otp/strategies/forti_authenticator.rb !45055 (diffs) we added a HTTP client to integrate with their API, so something similar should be possible here.

Forti docs https://drive.google.com/drive/u/1/folders/1d67dJ2cEuOMrTmPCR7_Vn41BGUwgIyYG (internal)