Move IFontHandle.ImFontLocked to ILockedImFont+impl

Dalamud/Interface/ManagedFontAtlas/ILockedImFont.cs

@@ -0,0 +1,21 @@
+using ImGuiNET;
+
+namespace Dalamud.Interface.ManagedFontAtlas;
+
+/// <summary>
+/// The wrapper for <see cref="ImFontPtr"/>, guaranteeing that the associated data will be available as long as
+/// this struct is not disposed.
+/// </summary>
+public interface ILockedImFont : IDisposable
+{
+    /// <summary>
+    /// Gets the associated <see cref="ImFontPtr"/>.
+    /// </summary>
+    ImFontPtr ImFont { get; }
+
+    /// <summary>
+    /// Creates a new instance of <see cref="ILockedImFont"/> with an additional reference to the owner.
+    /// </summary>
+    /// <returns>The new locked instance.</returns>
+    ILockedImFont NewRef();
+}