chore: add icon for NuGet packages (#742)

Co-authored-by: Florian Greinacher <florian@greinacher.de>

Author: soi013

System.IO.Abstractions.sln

@@ -19,7 +19,12 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Abstractions.Benc
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{BCEC61BD-4941-41EC-975A-ACEFC7AC1780}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.IO.Abstractions.Tests", "tests\System.IO.Abstractions.Tests\System.IO.Abstractions.Tests.csproj", "{7105D748-1253-409F-A624-4879412EF3C2}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Abstractions.Tests", "tests\System.IO.Abstractions.Tests\System.IO.Abstractions.Tests.csproj", "{7105D748-1253-409F-A624-4879412EF3C2}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "images", "images", "{F781892B-7C5D-4C8D-8D3D-3E9E207D686D}"
+	ProjectSection(SolutionItems) = preProject
+		images\icon_256x256.png = images\icon_256x256.png
+	EndProjectSection
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -51,10 +56,10 @@ Global
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {8885C59C-F6A0-4C2F-A3BC-B720E9BD161F}
-	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{7105D748-1253-409F-A624-4879412EF3C2} = {BCEC61BD-4941-41EC-975A-ACEFC7AC1780}
 	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {8885C59C-F6A0-4C2F-A3BC-B720E9BD161F}
+	EndGlobalSection
 EndGlobal

images/icon_256x256.png

@@ -4,6 +4,7 @@
         <RootNamespace>System.IO.Abstractions.TestingHelpers</RootNamespace>
         <Description>A set of pre-built mocks to help when testing file system interactions.</Description>
         <TargetFrameworks>net5.0;netstandard2.1;netstandard2.0;net461</TargetFrameworks>
+        <PackageIcon>icon_256x256.png</PackageIcon>
     </PropertyGroup>
     <ItemGroup>
         <ProjectReference Include="../System.IO.Abstractions/System.IO.Abstractions.csproj" />
@@ -14,4 +15,7 @@
             <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
         </PackageReference>
     </ItemGroup>
+    <ItemGroup>
+        <None Include="..\..\images\icon_256x256.png" Pack="true" PackagePath="\"/>
+    </ItemGroup>
 </Project>

src/System.IO.Abstractions.TestingHelpers/System.IO.Abstractions.TestingHelpers.csproj

@@ -4,6 +4,7 @@
     <RootNamespace>System.IO.Abstractions</RootNamespace>
     <Description>A set of abstractions to help make file system interactions testable.</Description>
     <TargetFrameworks>net5.0;netstandard2.1;netstandard2.0;net461</TargetFrameworks>
+    <PackageIcon>icon_256x256.png</PackageIcon>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.1' OR '$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.IO.FileSystem.AccessControl" Version="4.7.0"/>
@@ -17,4 +18,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
   </ItemGroup>
+  <ItemGroup>
+    <None Include="..\..\images\icon_256x256.png" Pack="true" PackagePath="\" />
+  </ItemGroup>
 </Project>