Change nuget backend packages

Delete Backend.Metal because is not needed anymore.
Do not include .metal in x86_64 binaries

LLama/runtimes/build/LLamaSharp.Backend.Cpu.nuspec

@@ -19,10 +19,9 @@
     <file src="LLamaSharpBackend.props" target="build/netstandard2.0/LLamaSharp.Backend.Cpu.props" />
     <file src="runtimes/libllama.dll" target="runtimes\win-x64\native\libllama.dll" />
     <file src="runtimes/libllama.so" target="runtimes\linux-x64\native\libllama.so" />
-    <file src="runtimes/libllama.dylib" target="runtimes\osx-x64\native\libllama.dylib" />
-    <file src="runtimes/ggml-metal.metal" target="runtimes\osx-x64\native\ggml-metal.metal" />
-    <file src="runtimes/libllama.dylib" target="runtimes\osx-arm64\native\libllama.dylib" />
-    <file src="runtimes/ggml-metal.metal" target="runtimes\osx-arm64\native\ggml-metal.metal" />
+    <file src="runtimes/macos-x86_64/libllama.dylib" target="runtimes\osx-x64\native\libllama.dylib" />
+    <file src="runtimes/macos-arm64/libllama.dylib" target="runtimes\osx-arm64\native\libllama.dylib" />
+    <file src="runtimes/macos-arm54/ggml-metal.metal" target="runtimes\osx-arm64\native\ggml-metal.metal" />
     <file src="icon512.png" target="icon512.png" />
   </files>
 </package>

LLama/runtimes/build/LLamaSharp.Backend.MacMetal.nuspec

@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<package >
-  <metadata>
-    <id>LLamaSharp.Backend.MacMetal</id>
-    <version>$version$</version>
-    <title>LLamaSharp.Backend.MacMetal, the backend for LLamaSharp on MACOS.</title>
-    <authors>llama.cpp Authors</authors>
-    <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <license type="expression">MIT</license>
-    <icon>icon512.png</icon>
-    <projectUrl>https://github.com/SciSharp/LLamaSharp</projectUrl>
-    <description>LLamaSharp.Backend.MacMetal is a backend for LLamaSharp to use MAC with GPU support.</description>
-    <releaseNotes></releaseNotes>
-    <copyright>Copyright 2023 The llama.cpp Authors. All rights reserved.</copyright>
-    <tags>LLamaSharp LLama LLM GPT AI ChatBot SciSharp</tags>
-  </metadata>
-
-  <files>
-    <file src="LLamaSharpBackend.props" target="build/netstandard2.0/LLamaSharp.Backend.MacMetal.props" />
-    <file src="runtimes/ggml-metal.metal" target="runtimes\osx-x64\native\ggml-metal.metal" />
-    <file src="runtimes/libllama.dylib" target="runtimes\osx-x64\native\libllama.dylib" />
-    <file src="runtimes/libllama.dylib" target="runtimes\osx-arm64\native\libllama.dylib" />
-    <file src="runtimes/ggml-metal.metal" target="runtimes\osx-arm64\native\ggml-metal.metal" />
-    <file src="icon512.png" target="icon512.png" />
-  </files>
-</package>

LLama/runtimes/build/LLamaSharpBackend.props

@@ -25,12 +25,6 @@
       <Visible>false</Visible>
       <Link>%(Filename)%(Extension)</Link>
     </Content>
-    <Content Include="$(MSBuildThisFileDirectory)\..\..\runtimes\osx-x64\native\*.metal"
-             Condition="'$(PlatformTarget)' == 'x64'">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-      <Visible>false</Visible>
-      <Link>%(Filename)%(Extension)</Link>
-    </Content>
 
     <Content Include="$(MSBuildThisFileDirectory)\..\..\runtimes\osx-arm64\native\*.dylib"
              Condition="'$(PlatformTarget)' == 'arm64'">