Makes map vote and roundstart smart about player count. (#5418)

* Makes map vote and roundstart smart about player count.
No more Saltern with 30 players, or Knight Ship with 50.

* a typo

* Address reviews.

* Localized.

Content.Server/Maps/GameMapPrototype.cs

@@ -0,0 +1,53 @@
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.Maps
+{
+    /// <summary>
+    /// Prototype data for a game map.
+    /// </summary>
+    [Prototype("gameMap")]
+    public class GameMapPrototype : IPrototype
+    {
+        /// <inheritdoc/>
+        [ViewVariables, DataField("id", required: true)]
+        public string ID { get; } = default!;
+
+        /// <summary>
+        /// Minimum players for the given map.
+        /// </summary>
+        [ViewVariables, DataField("minPlayers", required: true)]
+        public uint MinPlayers { get; }
+
+        /// <summary>
+        /// Maximum players for the given map.
+        /// </summary>
+        [ViewVariables, DataField("maxPlayers")]
+        public uint MaxPlayers { get; } = uint.MaxValue;
+
+        /// <summary>
+        /// Name of the given map.
+        /// </summary>
+        [ViewVariables, DataField("mapName", required: true)]
+        public string MapName { get; } = default!;
+
+        /// <summary>
+        /// Relative directory path to the given map, i.e. `Maps/saltern.yml`
+        /// </summary>
+        [ViewVariables, DataField("mapPath", required: true)]
+        public string MapPath { get; } = default!;
+
+        /// <summary>
+        /// Controls if the map can be used as a fallback if no maps are eligible.
+        /// </summary>
+        [ViewVariables, DataField("fallback")]
+        public bool Fallback { get; }
+
+        /// <summary>
+        /// Controls if the map can be voted for.
+        /// </summary>
+        [ViewVariables, DataField("votable")]
+        public bool Votable { get; } = true;
+    }
+}