Update Visual Basic Build Commands to Use dotnet build Instead of VBC

[shethaadit]

Summary

This PR updates the documentation to reflect the use of the modern dotnet build command for compiling Visual Basic applications, replacing references to the legacy Visual Basic command-line compiler (VBC).

Key Changes:

• Replaced mentions of VBC with dotnet build to align with current .NET build practices.
• Updated the description and the "Building from the Command Line" section to clarify that dotnet build is now the primary build tool for Visual Basic programs outside the Visual Studio IDE.
• Ensured all references are consistent with the modern .NET ecosystem.

Fixes #40060

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Internal previews

📄 File	🔗 Preview link
docs/visual-basic/reference/command-line-compiler/index.md	Visual Basic command-line compiler

[BillWagner]

Thanks @shethaadit

This LGTM, and I'll now.