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.

core/pom.xml

@@ -98,6 +98,14 @@
             <scope>provided</scope>
         </dependency>
 
+        <!-- Bedrock player bridge -->
+        <dependency>
+            <groupId>org.geysermc</groupId>
+            <artifactId>connector</artifactId>
+            <version>1.4.3-SNAPSHOT</version>
+            <scope>provided</scope>
+        </dependency>
+
         <!--Common component for contacting the Mojang API-->
         <dependency>
             <groupId>com.github.games647</groupId>