prevent rcd destroying planets (#16120)

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Shared/Maps/ContentTileDefinition.cs

@@ -75,6 +75,11 @@ namespace Content.Shared.Maps
         /// </summary>
         [DataField("weather")] public bool Weather = false;
 
+        /// <summary>
+        /// Is this tile immune to RCD deconstruct.
+        /// </summary>
+        [DataField("indestructible")] public bool Indestructible = false;
+
         public void AssignTileId(ushort id)
         {
             TileId = id;