Refactor CommandsExecutor - is no longer static singleton

Preparing for change in Command#handle,
which is going to take a CommandContext as an additional argument.
This way we can pass in command dependencies in a safe way
instead of requiring them to access static methods.

src/main/java/client/command/CommandContext.java

@@ -0,0 +1,6 @@
+package client.command;
+
+import database.drop.DropProvider;
+
+public record CommandContext(DropProvider dropProvider) {
+}

src/main/java/client/command/CommandsExecutor.java

@@ -43,16 +43,27 @@ import java.util.List;
 
 public class CommandsExecutor {
     private static final Logger log = LoggerFactory.getLogger(CommandsExecutor.class);
-    private static final CommandsExecutor instance = new CommandsExecutor();
     private static final char USER_HEADING = '@';
     private static final char GM_HEADING = '!';
 
     private final HashMap<String, Command> registeredCommands = new HashMap<>();
     private final List<Pair<List<String>, List<String>>> commandsNameDesc = new ArrayList<>();
+    private final CommandContext commandContext;
     private Pair<List<String>, List<String>> levelCommandsCursor;
 
-    public static CommandsExecutor getInstance() {
-        return instance;
+    public CommandsExecutor(CommandContext commandContext) {
+        this.commandContext = commandContext;
+        registerCommands();
+    }
+
+    private void registerCommands() {
+        registerLv0Commands();
+        registerLv1Commands();
+        registerLv2Commands();
+        registerLv3Commands();
+        registerLv4Commands();
+        registerLv5Commands();
+        registerLv6Commands();
     }
 
     public static boolean isCommand(Client client, String content) {
@@ -63,16 +74,6 @@ public class CommandsExecutor {
         return heading == USER_HEADING;
     }
 
-    private CommandsExecutor() {
-        registerLv0Commands();
-        registerLv1Commands();
-        registerLv2Commands();
-        registerLv3Commands();
-        registerLv4Commands();
-        registerLv5Commands();
-        registerLv6Commands();
-    }
-
     public List<Pair<List<String>, List<String>>> getGmCommands() {
         return commandsNameDesc;
     }