Say whose type it is

Two fields on the same page were both labelled "Type": the asset's own, and the
catalog model's. Only one of them was vague. "Model type" already says exactly
what it is; the bare "Type" did not say whose.

So the unqualified one is the one that changes. No new vocabulary, and "Model
type" reads correctly against it:

  Type  ->  Machine Type      (machines)
  Type  ->  PC Type           (computers)
  Type  ->  Printer Type      (printers)
  Type  ->  Device Type       (network devices)

Left alone everywhere the word is not ambiguous - measuring tools, subnets,
VLANs, notifications, supply types and the manifest editor have no model type on
screen to be confused with.

This is a labelling change only. It does not address the blank type column on
machines imported from the classic ASP database, which is a data gap the
backfill script fills; renaming a column heading was never going to put values
in it.

plugins/network/frontend/views/NetworkDevicesList.vue

@@ -58,7 +58,7 @@
                 <th>Asset Tag</th>
                 <th>Hostname</th>
                 <th>Serial Number</th>
-                <th>Type</th>
+                <th>Device Type</th>
                 <th>Vendor</th>
                 <th>Features</th>
                 <th>Status</th>