Move snapshot age conversion to client and round

Moves the age human conversion logic to the client so that this value
can be used by API consumers programatically.

Rounding ensures recent snapshots are not showing as "older" than they
actually are, which is important for accuracy especially with
automirror snapshots and ages above half the next rounding value.

daemon-common/common.py

@@ -486,34 +486,11 @@ def getDomainSnapshots(zkhandler, dom_uuid):
 
         _snap_timestamp = float(snap_timestamp)
         snap_age_secs = int(current_timestamp) - int(_snap_timestamp)
-        snap_age = f"{snap_age_secs} seconds"
-        snap_age_minutes = int(snap_age_secs / 60)
-        if snap_age_minutes > 0:
-            if snap_age_minutes > 1:
-                s = "s"
-            else:
-                s = ""
-            snap_age = f"{snap_age_minutes} minute{s}"
-        snap_age_hours = int(snap_age_secs / 3600)
-        if snap_age_hours > 0:
-            if snap_age_hours > 1:
-                s = "s"
-            else:
-                s = ""
-            snap_age = f"{snap_age_hours} hour{s}"
-        snap_age_days = int(snap_age_secs / 86400)
-        if snap_age_days > 0:
-            if snap_age_days > 1:
-                s = "s"
-            else:
-                s = ""
-            snap_age = f"{snap_age_days} day{s}"
-
         snapshots.append(
             {
                 "name": snap_name,
                 "timestamp": snap_timestamp,
-                "age": snap_age,
+                "age": snap_age_secs,
                 "xml_diff_lines": snap_dom_xml_diff,
                 "rbd_snapshots": snap_rbd_snapshots,
             }