Restructure VB.NET async article to follow C# breakfast tutorial format with proper VB syntax

[Copilot]

The Visual Basic async programming documentation was using an incorrect C# article as a reference and had an academic structure that didn't match the recommended tutorial approach. This PR completely restructures the VB.NET async article to follow the correct C# article format (https://learn.microsoft.com/en-us/dotnet/csharp/asynchronous-programming/) while using proper Visual Basic syntax throughout.

Key Changes

Complete structural overhaul:

• Replaced the academic article structure with the practical breakfast-making tutorial approach
• Changed from abstract concepts to concrete, progressive examples showing synchronous → simple async → concurrent async patterns
• Removed the technical diagram section and replaced with hands-on code examples

VB.NET breakfast tutorial implementation:

• Created comprehensive VB.NET breakfast code examples that mirror the C# tutorial structure
• All code uses proper Visual Basic syntax: Task(Of T), Async Function, Await, Module, etc.
• Progressive examples show the evolution from blocking synchronous code to efficient concurrent async code

Improved consistency and readability:

• All explanatory text now uses VB.NET method names and syntax consistently
• Replaced C#-style examples with idiomatic Visual Basic patterns
• Added proper VB.NET exception handling examples
• Updated all cross-references to use VB.NET conventions

Modern .NET alignment:

• Updated code snippets to target .NET 8.0
• Removed outdated references and aligned with current async/await best practices
• Added comparison between Async/Await and ContinueWith patterns in VB.NET

Enhanced documentation format:

• Converted all code snippets to the modern :::code format for better rendering
• Fixed relative links to follow documentation standards
• Added visual diagrams from the C# version to illustrate timing concepts
• Included proper AI-generated content disclosure

The article now provides the same high-quality tutorial experience as the C# version but with proper Visual Basic syntax and conventions throughout, eliminating the confusion reported in issue #17731.

Fixes #17731.
Fixes #37289 (duplicate).

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Internal previews

📄 File	🔗 Preview link
docs/visual-basic/programming-guide/concepts/async/index.md	Asynchronous programming with Async and Await (Visual Basic)

[BillWagner]

@copilot You picked the wrong C# article as a source. Use the one referenced in this comment: #17731 (comment)

The correct article is this one: https://learn.microsoft.com/en-us/dotnet/csharp/asynchronous-programming/ You can reuse those images for the VB article as well.

[Copilot]

@copilot You picked the wrong C# article as a source. Use the one referenced in this comment: #17731 (comment)

The correct article is this one: ht...

I've restructured the VB article to follow the correct C# article format using the breakfast tutorial approach. The article now uses the same progressive teaching structure (synchronous → simple async → concurrent async) but with proper VB.NET syntax throughout. All code examples have been converted to the breakfast metaphor with VB.NET conventions. Commit: 07fcef0

[BillWagner]

This is much closer. I have a few things to address and this will be ready.

[BillWagner]

@copilot Please address the remaining comments.

[Copilot]

@copilot Please address the remaining comments.

Addressed all remaining comments: fixed relative link, converted snippets to ::: format, copied and referenced all diagrams from the C# version, and ensured the project builds successfully. Commit: 41f0f0b

[BillWagner]

Once I upgrade to .NET 9, this is ready.