Provide names and pools when creating MiniYaml.

- Rename the filename parameter to name and make it mandatory. Review all callers and ensure a useful string is provided as input, to ensure sufficient context is included for logging and debugging. This can be a filename, url, or any arbitrary text so include whatever context seems reasonable.
- When several MiniYamls are created that have similar content, provide a shared string pool. This allows strings that are common between all the yaml to be shared, reducing long term memory usage. We also change the pool from a dictionary to a set. Originally a Dictionary had to be used so we could call TryGetValue to get a reference to the pooled string. Now that more recent versions of dotnet provide a TryGetValue on HashSet, we can use a set directly without the memory wasted by having to store both keys and values in a dictionary.

OpenRA.Mods.Common/Widgets/Logic/ServerListLogic.cs

@@ -456,7 +456,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 					var httpResponseMessage = await client.GetAsync(queryURL);
 					var result = await httpResponseMessage.Content.ReadAsStreamAsync();
 
-					var yaml = MiniYaml.FromStream(result);
+					var yaml = MiniYaml.FromStream(result, queryURL);
 					games = new List<GameServer>();
 					foreach (var node in yaml)
 					{
@@ -479,6 +479,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 				}
 
 				var lanGames = new List<GameServer>();
+				var stringPool = new HashSet<string>(); // Reuse common strings in YAML
 				foreach (var bl in lanGameLocations)
 				{
 					try
@@ -486,7 +487,8 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 						if (string.IsNullOrEmpty(bl.Data))
 							continue;
 
-						var game = new MiniYamlBuilder(MiniYaml.FromString(bl.Data)[0].Value);
+						var game = new MiniYamlBuilder(MiniYaml.FromString(
+							bl.Data, $"BeaconLocation_{bl.Address}_{bl.LastAdvertised:s}", stringPool: stringPool)[0].Value);
 						var idNode = game.NodeWithKeyOrDefault("Id");
 
 						// Skip beacons created by this instance and replace Id by expected int value