Implement an enabled/disabled setting for CI purposes

Problem/Motivation

Our automatic tests are being prevented from using the one time login link, because they are blocked, which seems reasonable; it is automated access, after all. We do have config split, so the issue is solveable, but not in a very elegant way; we need to add this module to all environments where we want it. It would be a lot more convenient if the module had an "Enabled" configuration setting that we could enable by default, and only for our CI pipelines add a "disabled" config setting to the relevant split. For example, the TFA module → follows this pattern.

Steps to reproduce

N/A.

Proposed resolution

Add a configuration option "Enabled" to this module.

Remaining tasks

Implement
Review

User interface changes

There will be an extra checkbox in the settings screen.

API changes

None.

Data model changes

None.