CI: Check that protocol reported data types match the values

More detail: #740, #134
UPDATE: Also #266 and #2549

Information reported via NUT networked protocol (from `upsd`) allegedly has mismatched assigned data types (e.g. obvious strings are marked as NUMBERs). This issue is two-fold: confirm whether this happens, and rectify it. Maybe sanity-checks in emitting code. Certainly some test in the NIT suite will be welcome.