Remove Private Tokens

To do:

• Remove Private API Token from profile/account
• Remove API::Session which can be used to get the private token when providing username/password
• Remove UserWithPrivateDetails entity.
• Remove all API/web authentication using private_token or authentication_token (they're the same thing)
• Sudo scope (lib/api/helpers.rb:432)
• Migrate Private tokens to PATs with the api scope, as well as the sudo scope if the user is an admin (depends on https://gitlab.com/gitlab-org/gitlab-ce/issues/38447)
• Remove users.authentication_token
• Update API docs (doc/api/README.md, doc/user/profile/personal_access_tokens.md)
• Move RSS and incoming email tokens to Access Tokens (app/views/profiles/accounts/show.html.haml)
• Fix specs
• Add new specs
• Add changelog item

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/38595 and https://gitlab.com/gitlab-org/gitlab-ce/issues/38447

changed the description

marked the checklist item Sudo scope (lib/api/helpers.rb:432) as completed

added 31 commits

• 47099996...1e4b75ba - 22 commits from branch master
• da85031d - Remove Private Token from User Settings > Account
• d5a362ea - Remove Session API
• 9464f268 - Remove private_token from API user entity
• fbdc90d4 - Remove gitlab:users:clear_all_authentication_tokens rake task
• f2514950 - Remove tokens:reset_all_auth rake task
• 0ac33914 - Remove authentication using user.private_token
• 76d9ecfd - Remove User#private_token
• a5d371ce - Consistently use PersonalAccessToken instead of PersonalToken
• 089b3196 - Add sudo API scope

Compare with previous version

marked the checklist item Migrate Private tokens to PATs with the api scope, as well as the sudo scope if the user is an admin (depends on https://gitlab.com/gitlab-org/gitlab-ce/issues/38447) as completed

marked the checklist item Remove users.authentication_token as completed

added 2 commits

• 8b0ada8e - Migrate user private tokens to personal access tokens
• 6445564b - Remove user authentication_token column

Compare with previous version

@rspeicher Can you please review the code while I update the docs?

assigned to @rspeicher

changed the description