🔒 : secure "/api/state" endpoint

[juwit]

Is your feature request related to a problem? Please describe.
/api/state endpoint may expose sensitive information.
This endpoint MUST be secured.
terraform httpd backend supports BASIC http authentication, so /api/state should support this kind of auth.
When the endpoint is secured, the backend configuration should be generated using credentials that allow a specific module to connect to its backend.

See https://www.terraform.io/docs/backends/types/http.html

Describe the solution you'd like
Maybe we should generate a "one-time" couple of credentials when generating a backend configuration for a stack. Or at least, a unique couple of credentials for each stack, so that a stack owner cannot see other stacks information.
We may need to implement a custom spring UserDetailsService for this purpose.

Describe alternatives you've considered
N/A

Additional context
N/A