[Feature] Update Manager integration for PBS

[jostrasser]

Describe the feature

It would be helpful to integrate the Update Checks (Update Manager) also for Proxmox Backup Servers (PBS)

Use Case

To check for updates centrally (also for PBS).

Alternatives considered

none

How important is this for you?

medium, general as Feature Request to make PegaProx better ;)

Checklist

• I have searched existing issues and discussions to make sure this hasn't been requested before

[MrMasterbay]

added with v0.9.6.1

[bradyloveland]

@MrMasterbay how do I run an update for PBS now? I see the available updates for all of my pbs servers if I refresh while looking at a cluster, however there doesn't appear to be a button to update the pbs'?