Improve consistency by using campaign eligibility instead of linking status in all places

gui.py

@@ -1409,7 +1409,7 @@ class InventoryOverview:
             takefocus=False,
         ).grid(column=1, row=2, sticky="w", padx=4)
         # Linking status
-        if campaign.linked:
+        if campaign.eligible:
             link_kwargs = {
                 "style": '',
                 "text": _("gui", "inventory", "status", "linked"),

twitch.py

@@ -1521,7 +1521,7 @@ class Twitch:
         ]
         campaigns.sort(key=lambda c: c.active, reverse=True)
         campaigns.sort(key=lambda c: c.upcoming and c.starts_at or c.ends_at)
-        campaigns.sort(key=lambda c: c.linked, reverse=True)
+        campaigns.sort(key=lambda c: c.eligible, reverse=True)
 
         self._drops.clear()
         self.gui.inv.clear()