CI_JOB_TOKEN - new allowlist setting

Problem to solve

Following 18.0, the CI job token allowlist will be required for all projects utilizing CI job token. However, there might be a reason to turn off job token access for a specific project.

Proposal

To do this, we will introduce a toggle that acts as an on/off switch. When off, access is denied. When on, the allowlist is enabled.

Intended users

Feature Usage Metrics

We will keep track of whether or not users have chosen to "shut off" access to the project.

Does this feature require an audit event?

No, but it is a nice to have (to track who turned access on and off)