Add Roslyn5000 CodeFixers project to solution

Add a new CommunityToolkit.Mvvm.CodeFixers.Roslyn5000.csproj targeting net10.0 with ImplicitUsings and Nullable enabled, and include the project in dotnet.slnx. This adds a Roslyn5000-specific CodeFixers project to the solution so it can be built and discovered by the solution tooling.

Author: Sergio0694

dotnet.slnx

@@ -53,6 +53,7 @@
   <Project Path="src/CommunityToolkit.HighPerformance/CommunityToolkit.HighPerformance.csproj" />
   <Project Path="src/CommunityToolkit.Mvvm.CodeFixers.Roslyn4001/CommunityToolkit.Mvvm.CodeFixers.Roslyn4001.csproj" />
   <Project Path="src/CommunityToolkit.Mvvm.CodeFixers.Roslyn4120/CommunityToolkit.Mvvm.CodeFixers.Roslyn4120.csproj" />
+  <Project Path="src/CommunityToolkit.Mvvm.CodeFixers.Roslyn5000/CommunityToolkit.Mvvm.CodeFixers.Roslyn5000.csproj" />
   <Project Path="src/CommunityToolkit.Mvvm.CodeFixers/CommunityToolkit.Mvvm.CodeFixers.shproj" />
   <Project Path="src/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4001/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4001.csproj" />
   <Project Path="src/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4031/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4031.csproj" />

src/CommunityToolkit.Mvvm.CodeFixers.Roslyn5000/CommunityToolkit.Mvvm.CodeFixers.Roslyn5000.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>