[main] Source code updates from dotnet/dotnet (#12862)

> [!NOTE]
> This is a codeflow update. It may contain both source code changes
from
> [the VMR](https://github.com/dotnet/dotnet)
> as well as dependency updates. Learn more
[here](https://github.com/dotnet/dotnet/tree/main/docs/Codeflow-PRs.md).

This pull request brings the following source code changes

[marker]: <> (Begin:91fa59f1-1864-46b1-b482-87955691317c)

## From https://github.com/dotnet/dotnet
- **Subscription**:
[91fa59f1-1864-46b1-b482-87955691317c](https://maestro.dot.net/subscriptions?search=91fa59f1-1864-46b1-b482-87955691317c)
- **Build**:
[20251202.5](https://dev.azure.com/dnceng/internal/_build/results?buildId=2851916)
([293020](https://maestro.dot.net/channel/8298/github:dotnet:dotnet/build/293020))
- **Date Produced**: December 2, 2025 11:00:49 PM UTC
- **Commit**:
[78c39718bb6e8008ba9d2dbd00d550bee6be9f59](dotnet/dotnet@78c3971)
- **Commit Diff**:
[3b5d49b...78c3971](dotnet/dotnet@3b5d49b...78c3971)
- **Branch**: [main](https://github.com/dotnet/dotnet/tree/main)

[marker]: <> (End:91fa59f1-1864-46b1-b482-87955691317c)
[marker]: <> (Start:Footer:CodeFlow PR)

## Associated changes in source repos
-
dotnet/efcore@f564ef9...de10f40
-
dotnet/fsharp@5aa719d...61c1a22
-
6ae7bab...dd27cf3
-
dotnet/source-build-assets@a3edc67...feab92a
-
microsoft/vstest@81d120f...154e8ba
-
dotnet/windowsdesktop@9d90f3f...132afba

<!--
    To diff the source repo and PR branch contents locally, run:
darc vmr diff --name-only
https://github.com/dotnet/dotnet:78c39718bb6e8008ba9d2dbd00d550bee6be9f59..https://github.com/dotnet/msbuild:darc-main-adab706a-5155-4f90-b7be-20b3590dfc67
-->
[marker]: <> (End:Footer:CodeFlow PR)

---------

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
-  <Source Uri="https://github.com/dotnet/dotnet" Mapping="msbuild" Sha="3b5d49bb1053c228d431a7ea95a8bec6f9f16ab1" BarId="292651" />
+  <Source Uri="https://github.com/dotnet/dotnet" Mapping="msbuild" Sha="78c39718bb6e8008ba9d2dbd00d550bee6be9f59" BarId="293020" />
   <ProductDependencies>
     <!-- Necessary for source-build. This allows the live version of the package to be used by source-build. -->
     <Dependency Name="System.CodeDom" Version="9.0.11">