Further work on static side

PkmnLib.Static/Libraries/GrowthRateLibrary.cs

@@ -0,0 +1,30 @@
+using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Static.Libraries;
+
+/// <summary>
+/// The library for all growth rates in the game.
+/// </summary>
+public interface IReadOnlyGrowthRateLibrary
+{
+    /// <summary>
+    /// Tries to get a growth rate from the library. Returns false if the growth rate is not found.
+    /// </summary>
+    bool TryGet(StringKey key, [MaybeNullWhen(false)] out IGrowthRate value);
+    /// <summary>
+    /// Gets a random growth rate from the library. 
+    /// </summary>
+    IGrowthRate GetRandom(IRandom random);
+    /// <summary>
+    /// Gets the amount of growth rates in the library.
+    /// </summary>
+    int Count { get; }
+    /// <summary>
+    /// Whether the library is empty.
+    /// </summary>
+    bool IsEmpty { get; }
+}
+
+/// <inheritdoc cref="IReadOnlyGrowthRateLibrary"/>
+public class GrowthRateLibrary : DataLibrary<IGrowthRate>, IReadOnlyGrowthRateLibrary;