Feature: Creation of custom menu entries

[Metal-Mighty]

Is your feature request related to a problem? Please describe.
It could be nice to be able to add custom menu entries, either with quick links to specific internal resources, or resources external to the portal (monitoring solution, documentation, ticketing site, ...)

Describe the solution you'd like
Make it possible to create the aforementioned menu entries from the UI (with RBAC when implemented) and from the API. The links would be in a separate section. We should be able to decide the order of the menu entries in this section, and also where to put this section (first, last, somewhere between existing menu entries...)

Describe alternatives you've considered
N/A

Additional context
We have a lot of web resources linked to our IoT solution on-site and we would like to make it easier for our user to navigate to them if they don't have all the links