windows: move ffmpeg bins to submodule

udpate ffmpeg to b1cbeabf5e4b3234e895a58bafa371bfb792baf0
enable ffmpeg on arm64

Source/Core/DolphinTool/DolphinTool.vcxproj

@@ -15,14 +15,6 @@
     <Import Project="$(VSPropsDir)PCHUse.props" />
   </ImportGroup>
   <PropertyGroup Label="UserMacros" />
-  <ItemDefinitionGroup>
-    <Link>
-      <AdditionalDependencies>avrt.lib;iphlpapi.lib;winmm.lib;setupapi.lib;rpcrt4.lib;comctl32.lib;Shlwapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <AdditionalDependencies Condition="'$(Platform)'=='x64'">opengl32.lib;avcodec.lib;avformat.lib;avutil.lib;swresample.lib;swscale.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <AdditionalLibraryDirectories Condition="'$(Platform)'=='x64'">$(ExternalsDir)ffmpeg\lib;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
-      <SubSystem>Console</SubSystem>
-    </Link>
-  </ItemDefinitionGroup>
   <ItemGroup>
     <ProjectReference Include="$(CoreDir)DolphinLib.vcxproj">
       <Project>{D79392F7-06D6-4B4B-A39F-4D587C215D3A}</Project>