feat: GtkSharp net6 workload

[trungnt2910]

A .NET 6 Workload for GtkSharp. Should close #349.

What it can do:

Allow projects like this:

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

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net6.0-gtk</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <None Remove="**\*.glade" />
    <EmbeddedResource Include="**\*.glade">
      <LogicalName>%(Filename)%(Extension)</LogicalName>
    </EmbeddedResource>
  </ItemGroup>

</Project>

to build, run and publish correctly, with a unique net6.0-gtk TFM and no package references.

Some changes I made:

• Added a strong name key. The CreateFrameworkListFile target from Microsoft.DotNet.SharedFramework.Sdk, used to generate reference and runtime library packs, requires input assemblies to be signed, as it checks for a non-null PublicKeyToken. Furthermore, other .NET workload packs I know (Tizen, Xamarin,...) also have strong names.
• Edited a few Directory.Build.props file, so that the workloads and the libraries can share a few build variables. This makes it easier for workload build scripts to locate output libraries for frameworks.

I hope this pull request can be considered. If there's anything in this PR against the project's rules, please let me know as soon as possible so that I can quickly fix the problem.

[trungnt2910]

A question about templates:
Other workloads also provide templates for the .NET SDK.
GtkSharp already has templates, however, these use the net6.0 TFM and references GtkSharp as a NuGet package.
Should I modify these files directly in this PR and include the existing templates in the workload, or make a separate workload template pack?

[lytico]

i would prefer separate workload template pack

[trungnt2910]

i would prefer separate workload template pack

Done. I've added the workload packs for the three languages.
The templates in the workload pack:

• Have Workload in their package names.
• Use the target framework net6.0-gtk instead of net6.0 and do not reference the GtkSharp package.
• Allow creating applications using dotnet new gtk instead of dotnet new gtkapp (to ensure parity with other workloads, such as dotnet new macos and dotnet new android, as well as avoiding clashes with the existing gtkapp templates).

[thomiel]

We had some testing of the .NET 6 workload at #maui-linux:matrix.org and it proved ok to use, although there seems to be an issue with the templates on Linux that is still under investigation. This is how you would test it (including a hack to make the templates appear) on Ubuntu 22.04:

# install dotnet 6
sudo apt-get update; \
sudo apt-get install -y apt-transport-https && \
sudo apt-get update && \
sudo apt-get install -y dotnet-sdk-6.0

# add keys
wget https://packages.microsoft.com/config/ubuntu/22.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb

# install gtksharp with dotnet 6 support
git clone https://github.com/trungnt2910/GtkSharp.git
cd GtkSharp
sudo dotnet tool restore
sudo dotnet cake --BuildTarget=InstallWorkload 

# hack for making the templates visible in dotnet new
sudo cp /usr/share/dotnet/template-packs/* /usr/share/dotnet/templates/6.0.5

# install gtk
sudo apt-get install libgtk-3-0

# test gtk template
cd ..
mkdir gtksharptest
cd gtksharptest
dotnet new gtk
dotnet run

Having this included in an official release would be useful for our effort to establish Linux support for .NET MAUI (Multi-platform App UI).

[harry-cpp]

Well, I'm low on time, so its time to merge first and ask questions later :D

Thanks @trungnt2910 !

[knocte]

@harry-cpp AFAIU, there's no version in nuget that has the feature yet. Why hasn't there been a release recently?

[trungnt2910]

You might want to upvote #355.