Allow creating Personal Access Tokens through the website

Related to #2979

• Allow a user to create personal access tokens, and use them to authenticate
• Refactor API::Helpers into API::Helpers::Core and API::Helpers::Authentication

Tasks

• #2979 (!3749 (merged)) - Personal Access Tokens
  • Basic Implementation
    • Add UI to add "Personal Access Tokens"
    • Reload lib/api on every request
    • Respect these tokens for API requests
    • Just a param or a header too?
    • Allow revoking tokens
    • Expire tokens
    • Left bar should have a "PAT" icon
    • Scopes?
    • Copy to Clipboard
    • Show active/inactive tokens separately
      • No need to check for expired/revoked in the appropriate places
    • Why does regular ApplicationController check for private token?
    • Support non-API requests
    • Revert (or work on) lib/api eager loading
  • Create MR
  • Refactoring
  • Fix tests
  • Write more tests
  • Add screenshots to MR
  • Add description of query performance to MR
  • Limit the number of queries in the personal_access_tokens page
  • Wait for CI to pass
  • Fix merge issues in schema.rb
  • Assign MR to endboss
  • Wait for feedback
  • Fix feedback
    • Wait for CI to pass
  • Assign to @rspeicher
  • Fix @rspeicher's comments
  • Wait for CI to pass
  • Assign back to @rspeicher
  • Write documentation and ping @axil
  • Wait for Axil to respond
  • Assign to endboss
  • Address Douwe's feedback
    • Use the private_token or authentication_token param instead of personal_access_token
    • Ditto for the header
  • Assign to endboss
  • Make sure CI is green
  • Address Douwe's feedback
    • Don't go through the authenticate_user_from_private_token! method, if a private token is supplied (or combine them)
    • In authenticate_user_from_personal_access_token! don't hit DB if token_string is nil
    • Use current_user.personal_access_tokens.build in the controller
    • Remove the "We aren't using personal_access_token as the root param" comment
    • No need for = "...", we can just have the Inactive ... #{...} on the next line in the view
    • Render dates in a (more) human format
    • CSS issue with table
    • Don't show the tokens in the UI indefinitely
    • How to implement scopes? Add-on to current impl? Doorkeeper?
  • Wait for @DouweM's comments about scopes
  • Address @DouweM's second review
    • Try not using native['innerHTML']
    • use contexts for all "when ..."
    • Ensure consistency (styling) with other pages for "You don't have any tokens" message
    • "Actions" table column doesn't need a label
    • %td can be moved outside of the if/else statement
    • The header title should be "Profile Settings"
    • Can this be a before_create, so we don't need to use generate?
    • If it couldn't be revoked, will we show an error?
    • If it couldn't be saved, will we show an error?
  • Merge master
  • Update CHANGELOG entry
  • Add tests for form errors?
  • Post screenshots
  • Tag @jschatz1 for review
  • Wait for build to pass
  • Respond to @jschatz1's comments
    • Hardcoded colors should be variables
    • Should not be allowed to chose a date in the past
    • Use the same table as in the Applications tab
    • button should say "Create Personal Access Token"
    • Float the revoke to the right on the a
    • Change revocation message. "Are you sure you want to revoke this certificate? This action cannot be undone."
    • Date stays selected and looks selected even though date is set as "never".
    • hover on the calendar button shifts (not caused by this MR - happens on milestones#new as well)
    • Don't use the panel for the created token
      • Use a normal flash for "Your new personal access token has been created"
      • Show the input (with the token) below it full width.
      • Put the "Make sure you save it - you won't be able to access it again." message near the input
    • Have the input highlight all on single click
  • Update screenshots
  • Merge master in + conflicts
  • Assign to @jschatz1 again
  • Respond to @jschatz1's comments
    • No button for clipboard, only link
    • text-danger
    • highlight fade on that area where the token was created
  • Make sure build is green
  • Assign to @jschatz1
  • Wait for build to pass
  • Respond to @DouweM's feedback
    • move the redirect_to out of the if/else
    • certificate -> token
    • datepicker back to text field
    • combine the get_user_from_private_token and get_user_from_personal_access_token methods in ApplicationController
    • combine the get_user_from_private_token and get_user_from_personal_access_token methods in lib/api/helpers
    • don't need the new constants
  • Wait for build to pass
  • Wait for merge

Screenshots