Add support for MSBuildTask for VS2026

[Kielek]

Fixes #1566

Add support for MSBuildTask for VS2026.

Now, there is no possibility to use 2026 without manually setting paths.

While reviewing, consider checking commit by commit. It brings explanations for the particular steps.

Needed for https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation

I confirm that the pull-request:

• Follows the contribution guidelines
• Is based on my own work
• Is in compliance with my employer

[Kielek]

quodana-scan is failing, due to following error:

2025/12/11 11:08:37 Starting from version 2023.2 release versions of Qodana Linters require connection to Qodana Cloud. 
To continue using Qodana, please ensure you have an access token and provide the token as the QODANA_TOKEN environment variable.
Obtain your token by registering at https://qodana.cloud/
For more details, please visit: https://www.jetbrains.com/help/qodana/cloud-quickstart.html
We also offer Community versions as an alternative. You can find them here: https://www.jetbrains.com/help/qodana/linters.html
✗  Qodana exited with code 1

[zvirja]

@matkoch Could we please merge this in? It's quite crucial for VS 2026 & C# 10 support

[Kielek]

Workaround.
You can call similar in your codebase:

            static void SupportVs2026IfAvailable()
            {
                // Typical installation folder: C:\Program Files\Microsoft Visual Studio\18\Enterprise\MSBuild\Current\Bin\amd64
                // Waiting for official support in Nuke package https://github.com/nuke-build/nuke/pull/1583

                string[] editions = ["Enterprise", "Professional", "Community", "Preview"];

                foreach (var edition in editions)
                {
                    var msBuildPath = Path.Combine(SpecialFolder(SpecialFolders.ProgramFiles).NotNull(),
                        $@"Microsoft Visual Studio\18\{edition}\MSBuild\Current\Bin\amd64\MSBuild.exe");

                    if (File.Exists(msBuildPath))
                    {
                        MSBuildPath = msBuildPath;
                        return;
                    }
                }
            }

Works fine for OTel .NET Auto, couple last months: open-telemetry/opentelemetry-dotnet-instrumentation#4706