Frontend: Add instance setting to toggle enforcement of CI_JOB_TOKEN scope for all projects
## Problem
With https://gitlab.com/gitlab-org/gitlab/-/issues/440697+ we introduced an instance setting to enforce CI Job Token Scope for all projects. However we still need to implement a ~frontend UI for administrators to toggle this setting.
**Note**: In %18.0 we will enable this setting by default. However, we want to give instance administrators the ability to disable (and re-enable) the enforcement if they need to.
This is a ~frontend issue representing a project-level setting. In https://gitlab.com/gitlab-org/gitlab/-/issues/440697+ we introduced the instance-level setting in the backend. However we need to adjust the UX for project-level setting when the job token scope is enforced at intance-level.
## Proposal
* Add UI for admin settings to enabled/disable this setting. This setting should describe clearly the effect of enabling this setting, pointing also to the docs page.
* When instance settings are enabled, hide the radio options and save button in the UI for all licenses at the project level. The instance-level settings for self-managed and dedicated licenses will be mentioned in the documentation, accessible through the "Learn more" link in the allowlist description.
* See mockups in the [**Design Section**](https://gitlab.com/gitlab-org/gitlab/-/issues/496647/designs/Instance_settings.png)
## Context
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166952#note_2137397998
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