Modernize 3DES examples

[svick]

Related to dotnet/runtime#79924.

This PR deletes some outdated and duplicate samples for 3DES, modernizes the C# version of the remaining sample and removes samples from the obsolete TripleDESCryptoServiceProvider class.

Also updates the remarks of TripleDESCryptoServiceProvider to link to the TripleDES.Create method.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-security, @vcsjones
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Related to dotnet/runtime#79924.

This PR deletes some outdated and duplicate samples for 3DES, modernizes the C# version of the remaining sample and removes samples from the obsolete TripleDESCryptoServiceProvider class.

Also updates the remarks of TripleDESCryptoServiceProvider to link to the TripleDES.Create method.

Author:	svick
Assignees:	-
Labels:	area-System.Security, community-contribution
Milestone:	-

[bartonjs]

This was already fixed in #8384. Not sure why the updated samples aren't showing up on there; but that's the structure and style that I rewrote these samples to, and would prefer to not change any of the styling.

[vcsjones]

@bartonjs I think your previous PR only addressed TripleDES. I don't see TripleDESCryptoServiceProvider in your linked PR.

[bartonjs]

In that case.. the text updates and deleting all of the examples that pertain specifically to TripleDESCryptoServiceProvider are welcome; but changing the C# 3DES example is not (because then it doesn't match the VB or CPP-CLI samples, or the AES/RC2/etc samples).

[bartonjs]

The 3DES core C# samples should remain as-is, so they are consistent across languages and similar classes.

[svick]

@bartonjs I think that having outdated C# examples is worse than being inconsistent.

I would be fine with updating examples for other classes or for the other languages (where possible), but I really think the primary examples should demonstrate modern coding styles.

[gewarren]

Let's just delete the C++ examples.

[learn-build-service-prod]

Learn Build status updates of commit 7422693:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/cpp/VS_Snippets_CLR_Classic/classic TripleDESCryptoServiceProvider Example/CPP/source.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/cpp/VS_Snippets_CLR/Cryptography.3DESCSP.CreateEncryptor.File/CPP/fileexample.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/cpp/VS_Snippets_CLR/Cryptography.3DESCSP.CreateEncryptor.Memory/CPP/memoryexample.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Security.Cryptography/TripleDES/Overview/Project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Security.Cryptography/TripleDES/Overview/source.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Security.Cryptography/TripleDESCryptoServiceProvider/Overview/fileexample.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Security.Cryptography/TripleDESCryptoServiceProvider/Overview/memoryexample.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_CLR_Classic/classic TripleDESCryptoServiceProvider Example/VB/source.vb	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DES.Create.File/VB/project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DES.Create.File/VB/project.vbproj	✅Succeeded
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DES.Create.Memory/project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DES.Create.Memory/project.vbproj	✅Succeeded
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DESCSP.CreateEncryptor.File/VB/fileexample.vb	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_CLR/Cryptography.3DESCSP.CreateEncryptor.Memory/VB/memoryexample.vb	✅Succeeded	n/a (file deleted or renamed)
xml/System.Security.Cryptography/TripleDES.xml	✅Succeeded	View
xml/System.Security.Cryptography/TripleDESCryptoServiceProvider.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel