add /language command (#780)

* Fix the following issues:
1. HashMap non-thread-safe issus
2. Fix the same problem in pr621, but use a better implementation

Add the following functions:
1. There is now a language cache inside getLanguage to prepare for different languages corresponding to different time zones where the accounts in the server are located

* add /language command,each account has their own Locate

src/main/java/emu/grasscutter/game/Account.java

@@ -8,6 +8,7 @@ import emu.grasscutter.utils.Utils;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import org.bson.Document;
 
@@ -28,10 +29,12 @@ public class Account {
 	private String token;
 	private String sessionKey; // Session token for dispatch server
 	private List<String> permissions;
+    private Locale locale;
 	
 	@Deprecated
 	public Account() {
 		this.permissions = new ArrayList<>();
+        this.locale = Grasscutter.getConfig().LocaleLanguage;
 	}
 
 	public String getId() {
@@ -96,6 +99,14 @@ public class Account {
 		return this.sessionKey;
 	}
 
+    public Locale getLocale() {
+        return locale;
+    }
+
+    public void setLocale(Locale locale) {
+        this.locale = locale;
+    }
+
 	/**
 	 * The collection of a player's permissions.
 	 */
@@ -166,5 +177,10 @@ public class Account {
 		if (!document.containsKey("permissions")) {
 			this.addPermission("*");
 		}
+
+        // Set account default language as server default language
+        if (!document.containsKey("locale")) {
+            this.locale = Grasscutter.getConfig().LocaleLanguage;
+        }
 	}
 }