add alias handling to server and database

MareSynchronosServer/MareSynchronosShared/Models/Alias.cs

@@ -0,0 +1,13 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace MareSynchronosShared.Models;
+
+public class Alias
+{
+    [Key]
+    [MaxLength(10)]
+    [Required]
+    public string AliasUID { get; set; }
+    public User User { get; set; }
+    public string UserUID { get; set; }
+}