Add VB examples for MailMessage

[dsychin]

Summary

Add VB examples for MailMessage

Fixes #981

Dear Maintainers,
I see that the other dotnet repos have the hacktoberfest topic.
Can you also add it to this repo?

[opbld30]

Docs Build status updates of commit 97ad182:

✅ Validation status: passed

File	Status	Preview URL	Details
samples/snippets/visualbasic/VS_Snippets_Remoting/NCLMailSync/vb/mail.vb	✅Succeeded	View
xml/System.Net.Mail/MailMessage.xml	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

• Try searching in the Docs contributor and Admin Guide
• See the frequently asked questions
• Post your question in the Docs support channel

[opbld30]

Docs Build status updates of commit 3f81355:

✅ Validation status: passed

File	Status	Preview URL	Details
samples/snippets/visualbasic/VS_Snippets_Remoting/NCLMailSync/vb/mail.vb	✅Succeeded	View
xml/System.Net.Mail/MailMessage.xml	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

• Try searching in the Docs contributor and Admin Guide
• See the frequently asked questions
• Post your question in the Docs support channel

[gewarren]

The preview looks good and I verified that the code compiles. @dsychin Thanks very much!

[gewarren]

I don't see where the From property is explicitly set, but this is not unique to the snippet you added.

[gewarren]

Same comment as for From - I don't see where it's being set.