[RFE] List / Support Unmanaged (non-Foreman) Hosts in Inventory List

[sadsfae]

It can be useful to list "unmanaged" hosts that are defined in QUADS in the inventory for two reasons:

• It could be confusing to users to have their hosts show up in assignments but not in inventory even though we do require hosts to be in Foreman to show up in inventory
• It could be useful for people who do not need or want Foreman to still use QUADS dynamic inventory and wiki, perhaps they do not actually provision or even move hosts but they want to benefit from the other elements of QUADS.

Proposal:

Modify https://github.com/redhat-performance/quads/blob/latest/src/quads/web/app.py#L253 to include a conditional that if a host is defined in QUADS but not present in Foreman it creates an "Unmanaged" category on /dashboard (inventory page).