Further work on static side

PkmnLib.Static/Libraries/NatureLibrary.cs

@@ -0,0 +1,33 @@
+using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Static.Libraries;
+
+/// <summary>
+/// The library for all natures in the game.
+/// </summary>
+public interface IReadOnlyNatureLibrary
+{
+    /// <summary>
+    /// Tries to get a nature from the library. Returns false if the nature is not found.
+    /// </summary>
+    bool TryGet(StringKey key, [MaybeNullWhen(false)] out INature value);
+
+    /// <summary>
+    /// Gets a random nature from the library.
+    /// </summary>
+    INature GetRandom(IRandom random);
+
+    /// <summary>
+    /// The amount of natures in the library.
+    /// </summary>
+    int Count { get; }
+
+    /// <summary>
+    /// Whether the library is empty.
+    /// </summary>
+    bool IsEmpty { get; }
+}
+
+/// <inheritdoc cref="IReadOnlyNatureLibrary"/>
+public class NatureLibrary : DataLibrary<INature>, IReadOnlyNatureLibrary;