Making CSWinRt into prop file for c# (#34225)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

more breaking out stuff

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## PR Checklist

- [ ] **Closes:** #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end user facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/EnvironmentVariables/EnvironmentVariablesUILib/EnvironmentVariablesUILib.csproj

@@ -1,8 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <!-- Look at Directory.Build.props in root for common stuff as well -->
+  <Import Project="..\..\..\Common.Dotnet.CsWinRT.props" />
 
   <PropertyGroup>
     <OutputType>Library</OutputType>
-    <TargetFramework>net8.0-windows10.0.20348</TargetFramework>
     <RootNamespace>EnvironmentVariablesUILib</RootNamespace>
     <UseWinUI>true</UseWinUI>
     <EnablePreviewMsixTooling>true</EnablePreviewMsixTooling>
@@ -36,25 +37,7 @@
     <Content Remove="Assets\**\*.ico" Pack="false" />
   </ItemGroup>
 
-  <PropertyGroup Condition="'$(Configuration)'=='Debug'">
-    <DebugSymbols>true</DebugSymbols>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <DebugType>full</DebugType>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <Optimize>false</Optimize>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(Configuration)'=='Release'">
-    <DefineConstants>TRACE</DefineConstants>
-    <Optimize>true</Optimize>
-    <DebugType>pdbonly</DebugType>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-
   <ItemGroup>
-    <PackageReference Include="Microsoft.Windows.CsWinRT" />
     <PackageReference Include="Microsoft.Extensions.Hosting" />
     <PackageReference Include="Microsoft.WindowsAppSDK" />
     <PackageReference Include="Microsoft.Windows.SDK.BuildTools" />