Add diagnostics related to attributes

[BillWagner]

Contributes to #49292

One of the latest C# 14 diagnostics related to attribute usage. Consolidate with existing error diagnostics.

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Internal previews

📄 File	🔗 Preview link
.github/prompts/error-consolidation.md	Copilot prompts to consolidate error codes.
docs/csharp/language-reference/compiler-messages/attribute-usage-errors.md	Resolve errors and warnings related to attribute declarations or attribute use in your code
docs/csharp/language-reference/toc.yml	docs/csharp/language-reference/toc
docs/csharp/misc/sorry-we-don-t-have-specifics-on-this-csharp-error.md	C# 14 errors begin here

[Copilot]

Pull Request Overview

This PR consolidates 24 attribute-related compiler error and warning documentation files into a single comprehensive article attribute-usage-errors.md. The consolidation groups errors into five logical categories: attribute arguments and parameters, attribute class requirements, attribute location context, predefined attributes, and conditional attribute usage.

Key Changes

• Created new consolidated article covering CS0243, CS0404, CS0415, CS0416, CS0447, CS0577, CS0578, CS0582, CS0609, CS0625, CS0629, CS0636, CS0637, CS0641, CS0646, CS0653, CS0657, CS0658, CS0685, CS7014, CS7046, CS7047, CS7067, and CS9331.
• Removed 20 individual error documentation files from docs/csharp/misc/.
• Added redirections for all moved errors to point to the new consolidated article.

Reviewed Changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 33 comments.

Show a summary per file

File	Description
docs/csharp/language-reference/compiler-messages/attribute-usage-errors.md	New consolidated article organizing attribute-related errors into thematic sections with resolution guidance
docs/csharp/language-reference/toc.yml	Added new entry for attribute-usage-errors.md with displayName listing all consolidated error codes; removed individual error entries; reformatted async-await-errors displayName
docs/csharp/misc/sorry-we-don-t-have-specifics-on-this-csharp-error.md	Removed error codes CS7014, CS7046, CS7047, CS7067, and CS9331 from the unspecified errors list
docs/csharp/misc/cs0243.md through cs0685.md	Deleted 20 individual error documentation files that are now consolidated
.openpublishing.redirection.csharp.json	Added 20 redirection entries mapping old error file paths to the new consolidated article
.github/prompts/error-consolidation.md	Updated prompt template to reference attribute-usage-errors.md as the destination file with instructions for consolidation

[meaghanlewis]

These changes LGTM!