[UUF] Update TypeBuilder.DefineMethodOverride code examples to target .NET 9

[Copilot]

Problem

The code examples for TypeBuilder.DefineMethodOverride at https://learn.microsoft.com/en-us/dotnet/api/system.reflection.emit.typebuilder.definemethodoverride?view=net-9.0#examples were using .NET Framework-specific APIs that are not available in .NET Core, .NET 5+, or .NET 9. This made the examples non-compilable for modern .NET versions despite being displayed on the .NET 9 documentation page.

Changes

Updated both C# and Visual Basic code examples to use modern .NET APIs:

C# Changes

• Updated Project.csproj to target net9.0 (was net48) and changed OutputType to Exe
• Replaced AppDomain.CurrentDomain.DefineDynamicAssembly() with AssemblyBuilder.DefineDynamicAssembly() (modern API pattern)
• Changed AssemblyBuilderAccess.RunAndSave to AssemblyBuilderAccess.Run (the RunAndSave option is not supported in .NET Core+)
• Updated DefineDynamicModule(name, fileName) to DefineDynamicModule(name) to match the modern method signature
• Removed ab.Save() call and related comment (assembly persistence is not supported in .NET Core+)

Visual Basic Changes

• Created Project.vbproj targeting net9.0 with OutputType set to Exe
• Applied the same API modernization changes as the C# version

Testing

Both examples now:

• Build successfully with .NET 9 SDK
• Run correctly and produce the expected output demonstrating DefineMethodOverride functionality
• Maintain the same educational value showing how to use explicit interface implementations with dynamic types

The core functionality demonstrated by the examples (using DefineMethodOverride to associate a method body with an interface method declaration) remains unchanged and works identically on .NET 9.

Fixes #[issue number]

Original prompt

Please make this code example compilable for .NET 9 instead of just .NET Framework: https://learn.microsoft.com/en-us/dotnet/api/system.reflection.emit.typebuilder.definemethodoverride?view=net-9.0#examples

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[Copilot]

Pull Request Overview

This PR updates the code examples for TypeBuilder.DefineMethodOverride to target .NET 9 instead of .NET Framework 4.8, making them compilable and runnable on modern .NET versions. The changes replace deprecated .NET Framework-specific APIs with their modern equivalents while preserving the educational purpose of demonstrating explicit interface implementation with dynamic types.

Key Changes:

• Migrated from .NET Framework 4.8 to .NET 9 with modern API patterns
• Replaced AppDomain.CurrentDomain.DefineDynamicAssembly() with AssemblyBuilder.DefineDynamicAssembly()
• Removed assembly persistence functionality (Save() method) which is not supported in .NET Core+

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
snippets/csharp/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/Project.csproj	Updated target framework from net48 to net9.0 and changed OutputType from Library to Exe
snippets/csharp/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/source.cs	Modernized reflection emit APIs and removed assembly save functionality
snippets/visualbasic/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/Project.vbproj	Created new project file targeting net9.0 as an executable
snippets/visualbasic/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/source.vb	Applied same API modernization changes as C# version

[BillWagner]

This LGTM @gewarren

Let's