Triggering a manual scan from user interface

[v1r7u]

Users should be able to request new scans from Frontend application.

To accomplish the goal, scanner apps should run in queue-listening mode. Then scan scheduling could be triggered from Backend service instead of separate k8s cron-jobs only as it is now.

I think this task could work as an enhancement on top of scanners-refactoring #91 and page with scan results #208

As an idea, the user interface could be similar to ci tools, when you can see previous runs and can schedule new ones.

Opened questions:

• User interface design
• How to support both options in the same product: queue-triggered scans and independent cron-jobs