Enhancement: Debug mode

[LuisRodriguezLD]

In order to facilitate development, I suggest we add a debugMode: boolean in the settings page.
If it's on, GET /api/passwordless/login?loginToken={tokenFromEmail} will never set is_active to false.

This allows the dev to use the same token multiple times without the need to generate a new one.
Another option would be to use NODE_ENV === 'development'

I'm happy to work on this if you think it fits your vision