Replace OfflinePlayer#getLastPlayed

Currently OfflinePlayer#getLastPlayed could more accurately be described
as "OfflinePlayer#getLastTimeTheirDataWasSaved".

The API doc says it should return the last time the server "witnessed"
the player, whilst also saying it should return the last time they
logged in. The current implementation does neither.

Given this interesting contradiction in the API documentation and the
current defacto implementation, I've elected to deprecate (with no
intent to remove) and replace it with two new methods, clearly named and
documented as to their purpose.

paper-server/src/main/java/org/bukkit/craftbukkit/CraftOfflinePlayer.java

@@ -262,6 +262,61 @@ public class CraftOfflinePlayer implements OfflinePlayer, ConfigurationSerializa
         return this.getData() != null;
     }
 
+    // Paper start
+    @Override
+    public long getLastLogin() {
+        Player player = getPlayer();
+        if (player != null) return player.getLastLogin();
+
+        CompoundTag data = getPaperData();
+
+        if (data != null) {
+            if (data.contains("LastLogin")) {
+                return data.getLong("LastLogin");
+            } else {
+                // if the player file cannot provide accurate data, this is probably the closest we can approximate
+                File file = getDataFile();
+                return file.lastModified();
+            }
+        } else {
+            return 0;
+        }
+    }
+
+    @Override
+    public long getLastSeen() {
+        Player player = getPlayer();
+        if (player != null) return player.getLastSeen();
+
+        CompoundTag data = getPaperData();
+
+        if (data != null) {
+            if (data.contains("LastSeen")) {
+                return data.getLong("LastSeen");
+            } else {
+                // if the player file cannot provide accurate data, this is probably the closest we can approximate
+                File file = getDataFile();
+                return file.lastModified();
+            }
+        } else {
+            return 0;
+        }
+    }
+
+    private CompoundTag getPaperData() {
+        CompoundTag result = getData();
+
+        if (result != null) {
+            if (!result.contains("Paper")) {
+                result.put("Paper", new CompoundTag());
+            }
+            result = result.getCompound("Paper");
+        }
+
+        return result;
+    }
+    // Paper end
+
     @Override
     public Location getLastDeathLocation() {
         if (this.getData().contains("LastDeathLocation", 10)) {