Create stub GeyserService

The FloodgateService and GeyserService classes are not merged,
because Geyser can work without Floodgate.
Added Geyser as 'softdepends' in plugin.yml and bungee.yml
to make it load before FastLogin.
Also made Floodgate a soft dependency in bungee.yml.

velocity/src/main/java/com/github/games647/fastlogin/velocity/FastLoginVelocity.java

@@ -27,6 +27,7 @@ package com.github.games647.fastlogin.velocity;
 
 import com.github.games647.fastlogin.core.AsyncScheduler;
 import com.github.games647.fastlogin.core.hooks.FloodgateService;
+import com.github.games647.fastlogin.core.hooks.GeyserService;
 import com.github.games647.fastlogin.core.message.ChangePremiumMessage;
 import com.github.games647.fastlogin.core.message.ChannelMessage;
 import com.github.games647.fastlogin.core.message.SuccessMessage;
@@ -144,6 +145,11 @@ public class FastLoginVelocity implements PlatformPlugin<CommandSource> {
         return null;
     }
 
+    @Override
+    public GeyserService getGeyserService() {
+        return null;
+    }
+
     public FastLoginCore<Player, CommandSource, FastLoginVelocity> getCore() {
         return core;
     }