Add KosmicKrisp translation layer for macOS 26+

- Mesa 26.0 introduced KosmicKrisp, a Vulkan-on-Metal translation layer and the eventual successor to MoltenVK

nuget.config

@@ -2,6 +2,7 @@
 <configuration>
     <packageSources>
         <clear />
+        <add key="local" value="nuget" />
         <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
         <!-- Only needed when using pre-release versions of Ryujinx.LibHac. -->
         <add key="LibHacAlpha" value="https://git.ryujinx.app/api/packages/projects/nuget/index.json" />
@@ -10,6 +11,9 @@
     <packageSourceMapping>
         <!-- key value for <packageSource> should match key values from <packageSources> element -->
         <!-- These are defined and .NET still yells about multiple package sources with no mappings. Not sure what to do, this is in the docs lol -->
+        <packageSource key="local">
+            <package pattern="Ryujinx.Graphics.Vulkan.KosmicKrisp" />
+        </packageSource>
         <packageSource key="nuget.org">
             <package pattern="*" />
         </packageSource>