Project-level authorization settings

What problem will this feature address?

Basic auth security settings right now work on application-level. If I have multiple applications in my project I want to protect with the save Basic auth settings, I have to copy-paste the settings to each project. Mildly frustating when I want to change the password a lot of applications.

Describe the solution you'd like

At least Project-based basic auth settings, identifiable by a name.

Could also have:

• Toggle to auto-apply auth settings to all project applications, including newly configured applications.
• Instance-wide auth settings

Describe alternatives you've considered

This is already possible with the via Traefik File System dynamic/middlewares.yml, but is not user-friendly.

Additional context

I guess this fits in with #274.

Will you send a PR to implement it?

Yes

Start by tracing the existing application-level Basic auth settings and the Traefik middleware configuration referenced in dynamic/middlewares.yml. Review related issue #274 before narrowing the project-level scope, including named settings and optional propagation to current and newly configured applications. Done means the project-level behavior and its configuration flow are clearly implemented.