Update roslyn to 5.12.0-1.26453.19

[dibarbet]

Official Roslyn build: 20260903.19 (build 3066125)

View Complete Diff of Changes

• [main] Source code updates from dotnet/dotnet (PR: #85160)
• Allow Razor to supply editorconfig options during code action cleanup (PR: #85128)
• Stabilize transitive directive reload test (PR: #85138)
• Rationalize and simplify telemetry logging apis (PR: #85062)
• Fix completion crash with stale linked documents (PR: #85134)
• Fix AI artifact audit Copilot startup (PR: #85139)
• [main] Source code updates from dotnet/dotnet (PR: #85088)
• [main] Update dependencies from dotnet/roslyn (PR: #85099)
• Enable CI for dev/* branches (PR: #85144)
• Publish Windows PDBs for Roslyn SDK (PR: #85133)
• Use CollectionsMarshal to get span from list in collection expression (PR: #85007)
• Skip Roslyn SDK VSIX preparation under Core MSBuild (PR: #85137)
• Add GetValueConversion extension methods for ICoalesceOperation (PR: #85029)
• Use vscode-uri semantics for parsing URIs (PR: #83593)
• Remove testRunName from MacOS CI leg (PR: #85136)
• Unsafe evolution: fix a race in version decoding (PR: #85131)
• Prevent type rename from renaming ordinary Finalize methods (PR: #85126)
• Update the condition used to include the CodeStyle .globalconfig (PR: #80540)

[Copilot]

Copilot review overview

🟢 Approval recommended

The version bump and changelog entry are consistent, correctly formatted, and align with the repository’s Roslyn update/changelog guidance.

Review tier: Lite
Findings: None

What changed in this PR

Updates the default Roslyn language server version used by the VS Code C# extension and records the user-facing highlights in the changelog.

Changes:

• Bump defaults.roslyn to 5.12.0-1.26453.19.
• Add a filtered, user-facing Roslyn update entry under # 2.152.x in CHANGELOG.md.

File	Description
package.json	Updates the default Roslyn version string to the new build.
CHANGELOG.md	Adds a concise, user-facing set of Roslyn PR highlights for the new version.

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[dibarbet]

/azp run dotnet.vscode-csharp

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