[C# 13]: Remove What's new in C# 10

[BillWagner]

Visual Studio release

None

Link to speclet

• N/A

Link to Pull request

• N/A

New behavior

After G/A release look at C# 13 and C# 10 content. Make sure we do the following:

• Remove references to C# 10 as "new"
• Remove references to C# 13 as "preview" (except for the field feature)
• Retire the "What's New in C# 10" article. Incorporate all links and necessary content into the C# language history article.

Areas affected

• Add to What's new in C# 13: Add links to updated docs in the What's new in C# 13 article.
• Update language reference: Detail the areas in the language reference that will be updated for this feature.
• Update compiler messages: Add new (or updated) pages for new compiler messages. Include related message.
• Include in Everyday C# section*: Is this new feature included in Everyday C#?
• Tutorials: Are new tutorials required for this feature? If so, detail below

Language reference tasks

No response

Tutorial tasks

No response

Everyday C# tasks

No response

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Associated WorkItem - 340227