Further work on static side

PkmnLib.Static/Libraries/SpeciesLibrary.cs

@@ -0,0 +1,34 @@
+using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Species;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Static.Libraries;
+
+/// <summary>
+/// The library for all species in the game.
+/// </summary>
+public interface IReadOnlySpeciesLibrary
+{
+    /// <summary>
+    /// Tries to get a species from the library. Returns false if the species is not found.
+    /// </summary>
+    bool TryGet(StringKey key, [MaybeNullWhen(false)] out ISpecies value);
+
+    /// <summary>
+    /// Gets a random species from the library.
+    /// </summary>
+    ISpecies GetRandom(IRandom random);
+
+    /// <summary>
+    /// The amount of species in the library.
+    /// </summary>
+    int Count { get; }
+
+    /// <summary>
+    /// Whether the library is empty.
+    /// </summary>
+    bool IsEmpty { get; }
+}
+
+/// <inheritdoc cref="IReadOnlySpeciesLibrary"/>
+public class SpeciesLibrary : DataLibrary<ISpecies>, IReadOnlySpeciesLibrary;