Extend Machines list with additional filtering options

[siemenvdn]

Description

The Machines page already has search by name, but in larger deployments that's not always enough. This proposes adding a few extra filters on top of the existing search:

• User/owner
• Tag (e.g. tag:server, tag:exit-node)
• Status (online/offline/expired)
• Route (subnet routes, exit nodes)

Ideally filters are composable and preserved in the URL for bookmarking.