Add common page describing air-gap use case

Closes #39101

See merge request gitlab-org/gitlab!26167

Many commits squashed into one after I fought the danger-bot for more
time than I care to admin.

Add high-level steps of airgap

Add a link on Secure page & flesh out offline page more

Fix some markdown lint errors

Remove license scanning placeholder

Revert unintentional package change

Apply suggestion to
 doc/user/application_security/offline_deployments/index.md

Apply suggestion to
 doc/user/application_security/offline_deployments/index.md

Apply suggestion to
 doc/user/application_security/offline_deployments/index.md

Update text to mention package repos

Add SAST link

Address feedback given during the review

Add DAST link

Remove dependency scanning link until its merged

Enable Threat Monitoring page by default

See merge request gitlab-org/gitlab!22911

This enables the Threat Monitoring feature by default (and can be
disabled by explicitly disabling the `threat_monitoring` feature flag).

This also adds some basic documentation for Threat Monitoring.

Part of [WAF statistics reporting][1].

[1]: https://gitlab.com/gitlab-org/gitlab/issues/14707

Refactor approver classess into own class file for EE entities

See merge request gitlab-org/gitlab!27336

Merge branch '16143-add-editorconfig-to-keep-coding-style-consistance-for-different-ide-editors' into 'master'

Resolve "Add .editorconfig to keep coding style consistance for different IDE/Editors"

Closes #16143

See merge request gitlab-org/gitlab!25835

- enable easy sync of editor configs across
  team members and IDE's

Fix invalid LABEL directive

See merge request gitlab-org/gitlab!27257

Use GitLab Quality Team as maintainer of image

Fixed SSH warning style

See merge request gitlab-org/gitlab!26992

Swap to UNLINK for Redis set cache

See merge request gitlab-org/gitlab!27116

Add link to Gemnasium update frequency

Closes #210485

See merge request gitlab-org/gitlab!27241

Fix typo MRs

See merge request gitlab-org/gitlab!27302

Update link to public issue tracker (docs)

See merge request gitlab-org/gitlab!27265

Mention removal of redundant indexes when adding index

See merge request gitlab-org/gitlab!27100

When a new composite index is added, it might make an existing index
redundant.  So when adding an index, these redundant indexes should be
removed in the same migration.

Resolve "Add metrics for the size of the diff cache in redis"

Closes #37456

See merge request gitlab-org/gitlab!27048

I believe "in" is meant to be "is" here.

See merge request gitlab-org/gitlab!27186

Fix Conan package presenter to find correct files

See merge request gitlab-org/gitlab!27250

Conan::PackagePresenter now checks package
files to ensure the correct conan_package_reference
files are being returned in requests fixing a bug
where the first file by name was returned no matter
what request was made.

If UNLINK is not supported by the Redis server, we should
fall back to DEL. UNLINK was introduced in Redis 4.

This uses UNLINK in Redis 4 to delete sets. This unlinks the key
from the value but actually deletes the value asynchronously.
With large sets this should give us a reasonable performance boost.

This commit also implements multi-key deletes for RepositorySetCache
methods in the Repository model, meaning only one UNLINK call will be
issued for all sets being expired.

Update puma workers

See merge request gitlab-org/gitlab!27311

Make documentation a throughput label

See merge request gitlab-org/gitlab!26229

Releases Direct Links documentation

See merge request gitlab-org/gitlab!26370

Part of https://gitlab.com/gitlab-org/gitlab/issues/199065

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/26760

Add requirements index action

See merge request gitlab-org/gitlab!27205

Enable Redis cache key compression

Closes #198586

See merge request gitlab-org/gitlab!27254

Revert "Change iid argument to ID_TYPE for graphQL queries"

Closes #208394

See merge request gitlab-org/gitlab!27316

Add tab navigation to the package registry list view

See merge request gitlab-org/gitlab!26820

Fix rails console

See merge request gitlab-org/gitlab!27319

Make group_level_cycle_analytics enabled by default

See merge request gitlab-org/gitlab!27304