Skip or retain project while deleting the project

See merge request !1162

Update guide to migrate to 8.17 EE

See merge request !1177

Fix broken links to docs

See merge request !1179

[ci skip]

Implement backend for a read-only "Auditor" user

Closes #1439

See merge request !998

Read true-up info from license and validate it

Closes #550

See merge request !1159

adds select field and sync time migration for mirror sync cron jobs

Closes #99

See merge request !1115

Diplay correct message in git clients when License is not configured

See merge request !1133

We're also considering the scenario where historical data is present but
we don't have the number of previous seats which is the case when some
customers upgrade from CE.

- Allow the message to be returned from git_http controller
- Strip html chars from message returned via API

Squash binary files

See merge request !1174

Elasticsearch: allow initial indexing to proceed within Sidekiq

Closes #1618

See merge request !1144

- There's no real need to have this module _and_ `EE::User`

- This commit moves the contents of `EE::AuditorUser` to `EE::User`

Refactor the EE::User module

Changed ratio button label from Audit to Auditor, also
changed "Admin" label to "Access level"

Prior to this commit, the `index_statuses` table was allowed to go stale after
initial indexing. This made it impossible to provide status details, and also
made treating the initial index as a 'backfill' job harder.

Now, if a repository is indexed via `git push`, the initial indexing will
recognise that it has been indexed, and not re-index it.

We introduce an asynchronous initial indexer and an index status rake task at
the same time.

Use partials and backport code where necessary.

There were failures related to cross-spec contamination of the `License` mocks.

1. The edit user page allows making a user an admin or an auditor. This creates
   a virtual attribute called `access_level` which can have `regular`, `admin`,
   or `auditor` as valid values.

2. The `access_level=` method was broken, which led to the page not accepting
   changes to a user's access level.

3. This commit fixes the issue and adds specs for `access_level=`

Mainly related to increasing compatibility with CE, and trying to avoid merge
conflicts.

1. Create an `EE::AuditorUser` module with auditor-specific methods. Mixed into
   the `User` model.

2. Create an `EE::User` module with EE-specific user methods. Mixed into the
   `User` model.

3. Don't block creation of regular users when the auditor addon is disabled (bug
   in original implementation).

Changed the access checkboxes to radio buttons as to only
allow one particular type of user active at all times.

The new user types are as follows:
* Regular
* Auditor
* Admin

1. The add-on is named `GitLab_Auditor_User`

2. An auditor user cannot be created if the addon is not present.

3. `auditor?` always returns `false` if the addon is not present.

1. `add_column_with_default` needs a `down` block

2. Add specs for the auditor user to `spec/features/security`. This directory
   contains a series of feature specs to test the access various user roles have
   to various project/admin pages, which is the perfect place to test auditor
   user access.

3. Other minor changes (views, typos)

1. Projects under the groups they belong to, or under their own personal
   namespace. They cannot create projects under groups they don't have explicit
   control over.

2. Since we're thinking of auditor users as "regular users with readonly access
   to everything they wouldn't normally see", it makes sense to let them do
   anything a regular user would do, including creating projects and groups.

The `ProjectPolicy` is meant to be declarative in nature, and it isn't
necessarily a good idea to remove all duplication here. That level of
indirection would _hurt_ readability, rather than improve it.

1. Extract an `admin_or_auditor?` method to clean up multiple uses of
  `user.admin? || user.auditor?`

2. Follow the four phase test rule.

3. Clean up the `project_policy_spec` by using %i for literal symbols

4. A number of other minor improvements.