Fixes #19789 - fix Layout/SpaceAroundOperators cop
Fixes #19877 - Fix Style/NegatedIf cop
Fixes #19828 - Fix Rails/Blank cop
I disabled the default UnlessPresent value since sometimes it's clearerto use `unless attribute.present?` instead of `if attribute.blank?`.
Refs #3809 - Turning on the AndOr cop
Refs #3809 - Turning on some rubocop cops
Refs #3809 - Remove cops for empty lines
Fixes #7233 - Drop Ruby 1.8.7 and revert Ruby 1.8.7 specifics
Refs #3809 - Remove rubocop TODOs
Removed the following TODOs so that cops for these will run from now on:
Lint/AmbiguousOperator, DefEndAlignment, DeprecatedClassMethodsEnsureReturn, RequireParentheses, Void, BlockAlignment, EndAlignment,UselessAccessModifier,...
fixes #3892 - process REMOTE_USER_GROUP_N and REMOTE_USER_GROUP_#, add user to groups based on external user groups.
fixes #3528 - Populate first name, last name, and email, if available.
Fixes #3753 - always use main_app to determine paths for running an isolated namespace plugin
fixes #3312 - support /users/extlogin as a login page based on REMOTE_USER
fixes #2988 - merge authentication code, enables REMOTE_USER auth on new API controllers
fixes #2411 - move files in /models to /concerns, /services, /mailers, /observers