VSCODEEXT-353: Document Qt C# extension

[leena-miettinen]

• Add a section to the Overview
• Add a tutorial that describes the sample project

https://qt-project.atlassian.net/jira/software/c/projects/VSCODEEXT/boards/672?selectedIssue=VSCODEEXT-353

[kaheimri]

Please remove, this API is gone in the next release.

[kaheimri]

Please remove, this namespace is gone in the next release.

[kaheimri]

Qt Bridge for C# application

[kaheimri]

Replace with:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
    <QtBridgePackagePrefix>QtGroup.Qt.Bridge.CSharp</QtBridgePackagePrefix>
    <QtBridgeTemplateArch Condition="'$(QtBridgeTemplateArch)' == ''"
      >$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)</QtBridgeTemplateArch>
    <QtBridgeTemplateArch Condition="'$(QtBridgeTemplateArch)' == 'X64'">x64</QtBridgeTemplateArch>
    <QtBridgeTemplateArch Condition="'$(QtBridgeTemplateArch)' == 'Arm64'">arm64</QtBridgeTemplateArch>
    <QtBridgeTemplateRid Condition="'$(QtBridgeTemplateRid)' == '' and '$(RuntimeIdentifier)' != ''"
      >$(RuntimeIdentifier)</QtBridgeTemplateRid>
    <QtBridgeTemplateRid Condition="'$(QtBridgeTemplateRid)' == '' and $([MSBuild]::IsOSPlatform('Windows'))"
      >win-x64</QtBridgeTemplateRid>
    <QtBridgeTemplateRid Condition="'$(QtBridgeTemplateRid)' == '' and $([MSBuild]::IsOSPlatform('Linux'))"
      >linux-$(QtBridgeTemplateArch)</QtBridgeTemplateRid>
    <QtBridgeTemplateRid Condition="'$(QtBridgeTemplateRid)' == '' and $([MSBuild]::IsOSPlatform('OSX'))"
      >osx-$(QtBridgeTemplateArch)</QtBridgeTemplateRid>
    <QtBridgePackageId>$(QtBridgePackagePrefix).$(QtBridgeTemplateRid)</QtBridgePackageId>
  </PropertyGroup>

  <ItemGroup Condition="'$(QtBridgeTemplateRid)' == 'win-x64'
                    or '$(QtBridgeTemplateRid)' == 'linux-x64'
                    or '$(QtBridgeTemplateRid)' == 'osx-x64'
                    or '$(QtBridgeTemplateRid)' == 'osx-arm64'">
    <PackageReference Include="$(QtBridgePackageId)" Version="0.4.*-*" />
  </ItemGroup>

  <Target Name="EnsureSupportedQtBridgePlatform" BeforeTargets="Restore;Build"
          Condition="'$(QtBridgeTemplateRid)' != 'win-x64'
                  and '$(QtBridgeTemplateRid)' != 'linux-x64'
                  and '$(QtBridgeTemplateRid)' != 'osx-x64'
                  and '$(QtBridgeTemplateRid)' != 'osx-arm64'">
    <Error Text="Qt Bridge for C# currently supports win-x64, linux-x64, osx-x64, and osx-arm64. Selected RID: '$(QtBridgeTemplateRid)'." />
  </Target>

  <ItemGroup>
    <None Include="Main.qml"/>
    <Compile Include="Program.cs" />
  </ItemGroup>

</Project>

[kaheimri]

vscodeext-create-new-project-quick-csharp.webp isn't included in the PR

[kaheimri]

One final note i did not attach to the changes directly:

Framework picker step missing - the wizard's Framework prompt (net8.0/9.0/10.0) isn't mentioned in the walkthrough steps; net8.0 only appears unexplained in the final code sample.