Rework interactive tutorials

[BillWagner]

Fixes #50331
Fixes #50381

Reimagine the interactive tutorials that used Try.NET to introduce developers to the .NET platform.

Based on dotnet/try#1285, instead of Try.NET, use file-based apps in .NET 10 and GitHub codespaces to introduce developers to the platform without requiring an installation.

The current text uses the .NET template for the codespace. That works, but has extra features, and I'm working to get a new codespace for a minimal install. In the meantime, if you want to try the tutorials with the minimal set of features, open this (public) repository in codespaces: https://github.com/BillWagner/learn-csharp-codespaces

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Internal previews

📄 File	🔗 Preview link
docs/csharp/tour-of-csharp/tutorials/branches-and-loops.md	C# if statements and loops - conditional logic tutorial
docs/csharp/tour-of-csharp/tutorials/hello-world.md	Hello World - Introductory tutorial
docs/csharp/tour-of-csharp/tutorials/index.md	Introduction to C#
docs/csharp/tour-of-csharp/tutorials/list-collection.md	Learn to manage data collections using List<T> in C#
docs/csharp/tour-of-csharp/tutorials/numbers-in-csharp.md	docs/csharp/tour-of-csharp/tutorials/numbers-in-csharp
docs/csharp/tour-of-csharp/tutorials/pattern-matching.md	Match data against patterns
docs/csharp/tour-of-csharp/tutorials/tuples-and-types.md	Create types in C#

[BillWagner]

@meaghanlewis

This is ready for review, but not ready to merge. I'm waiting on creating the official codespace repo for these introductory tutorials.

[Copilot]

Pull request overview

This PR reimagines the interactive C# tutorials by replacing Try.NET with a GitHub Codespaces-based approach using file-based apps. Instead of running code in an in-browser interactive window, users now create files in GitHub Codespaces and execute them using dotnet commands in a terminal.

Key Changes:

• Migrated all tutorial content from Try.NET interactive snippets to GitHub Codespaces with file-based C# apps
• Consolidated code snippets into single executable .cs files (e.g., hello-world.cs, numbers.cs, tuples-types.cs)
• Removed project files (.csproj) as tutorials now use file-based apps
• Updated instructions to guide users through creating and running code in Codespaces

Reviewed changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
docs/csharp/tour-of-csharp/tutorials/index.md	Updated landing page to reference GitHub Codespaces instead of browser-based interactive experience
docs/csharp/tour-of-csharp/tutorials/hello-world.md	Converted from interactive tutorial to Codespaces-based tutorial with file creation and terminal execution instructions
docs/csharp/tour-of-csharp/tutorials/numbers-in-csharp.md	Reorganized to use file-based execution with methods; contains typos and duplicate content
docs/csharp/tour-of-csharp/tutorials/branches-and-loops.md	Converted to Codespaces approach with code refactoring into methods; has duplicate completion messages
docs/csharp/tour-of-csharp/tutorials/list-collection.md	Updated to use Codespaces with file-based execution; outdated description and command issue
docs/csharp/tour-of-csharp/tutorials/tuples-and-types.md	Converted to Codespaces format with file-based app approach; missing instructional context
docs/csharp/tour-of-csharp/tutorials/pattern-matching.md	Updated to use Codespaces and file-based execution with grammar issue
docs/csharp/tour-of-csharp/tutorials/snippets/HelloWorld/hello-world.cs	New consolidated code file replacing Program.cs
docs/csharp/tour-of-csharp/tutorials/snippets/NumbersInCsharp/Numbers.cs	Refactored code into multiple methods for better organization
docs/csharp/tour-of-csharp/tutorials/snippets/BranchesAndLoops/branches-loops.cs	Added new refactored code section with methods
docs/csharp/tour-of-csharp/tutorials/snippets/ListCollection/list.cs	New consolidated code file replacing Program.cs
docs/csharp/tour-of-csharp/tutorials/snippets/TuplesAndTypes/tuples-types.cs	New consolidated code file with incorrect variable names in output
docs/csharp/tour-of-csharp/tutorials/snippets/PatternMatching/patterns.cs	New consolidated code file replacing multiple separate files
*.csproj files	Deleted project files as tutorials now use file-based apps
Program.cs files	Removed old Program.cs files, replaced by new consolidated snippet files