Relates to #47424

This is mainly the setup of mutations for GraphQL. Including
authorization and basic return type-structure.

This method uses Gitlab::Profiler::TotalTimeFlatPrinter internally, which is the
same as RubyProf::FlatPrinter, but the min_percent option (and new max_percent
option) applies to the _total_ time, not the _self_ time. This helps us figure
out if we're calling a library inefficiently, for instance.

Making the `gettext:updated_check` by completely regenerating the gitlab.pot.

This avoids an issue where `gettext:find` would not pick up on changes
if the file isn't removed first.

This adds Keyset pagination to GraphQL lists. PoC for that is
pipelines on merge requests and projects.

When paginating a list, the base-64 encoded id of the ordering
field (in most cases the primary key) can be passed in the `before` or
`after` GraphQL argument.

Avoiding a count variable allows more natural translation in some languages.

This adds a reusable way to expose permissions for a user to types in
GraphQL.

This works the same way as change_column_type_using_background_migration, but
for renaming a column. It takes a table, not a relation, to match its concurrent
counterpart.

Also, generalise the cleanup migrations to reduce code duplication.

This was missed from
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20130

- I translate Discord too: https://crowdin.com/project/discord

A background column type change needs a cleanup step, like any background
migration. We should call that out explicitly in the documentation.