Redo mac bans - reduce amount of db queries on login

Works just like ip and hwid bans in that they are loaded on startup

src/main/java/server/ban/MacBanManager.java

@@ -0,0 +1,44 @@
+package server.ban;
+
+import database.ban.MacBan;
+import database.ban.MacBanRepository;
+import lombok.extern.slf4j.Slf4j;
+import net.jcip.annotations.ThreadSafe;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * @author Ponk
+ */
+@ThreadSafe
+@Slf4j
+public class MacBanManager {
+    private final MacBanRepository macBanRepository;
+    private final Set<String> bannedMacs = new HashSet<>();
+
+    public MacBanManager(MacBanRepository macBanRepository) {
+        this.macBanRepository = macBanRepository;
+    }
+
+    public synchronized void loadMacBans() {
+        List<MacBan> macBans = macBanRepository.getAllMacBans();
+        log.debug("Loaded {} mac bans", macBans.size());
+        bannedMacs.addAll(macBans.stream().map(MacBan::mac).toList());
+    }
+
+    public synchronized boolean isBanned(String mac) {
+        return bannedMacs.contains(mac);
+    }
+
+    public synchronized void banMac(String mac, int accountId) {
+        if (mac == null) {
+            throw new IllegalArgumentException("mac cannot be null");
+        }
+        // TODO: validate mac format. Or create "Mac" model class.
+
+        bannedMacs.add(mac);
+        macBanRepository.saveMacBan(accountId, mac);
+    }
+}