Prevent RefreshSignInAsync if it is called with wrong user

[wtgodbe]

Since this is a patch, instead of throwing an exception in cases where we wouldn't before like we do in the PR to main, we instead log an error and fail to refresh the cookie if RefreshSignInAsync is called with a TUser that does not have the same user ID as the currently authenticated user.

While this does not make it as obvious to developers that something has gone wrong, error logs are still pretty visible, and stale cookies are something web developers have to account for regardless. The big upside to not throwing in the patch is that we do not have to react to it in the email change confirmation flow to account for the possibility of RefreshSignInAsync throwing.

[Copilot]

Pull Request Overview

This PR prevents RefreshSignInAsync from throwing exceptions by logging errors and skipping the refresh when the supplied user does not match the authenticated user. It updates error handling in RefreshSignInAsync and adds new tests to verify the behavior in cases of unauthenticated requests and mismatched user IDs.

• Updated the RefreshSignInAsync method in SignInManager.cs to log appropriate error messages and return early.
• Adjusted existing tests and added new tests in SignInManagerTest.cs to verify that RefreshSignInAsync does not refresh the sign-in when conditions are not met.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Identity/test/Identity.Test/SignInManagerTest.cs	Updated and added tests to check that RefreshSignInAsync logs errors and does not invoke sign-in when the user is unauthenticated or mismatched.
src/Identity/Core/src/SignInManager.cs	Refactored RefreshSignInAsync to log error messages and abort refreshing sign-in when the user is not valid.

Comments suppressed due to low confidence (2)

src/Identity/test/Identity.Test/SignInManagerTest.cs:637

• [nitpick] The test method name 'ResignInNoOpsAndLogsErrorIfNotAuthenticated' may be ambiguous as it tests the RefreshSignInAsync behavior; consider renaming it to 'RefreshSignInNoOpsAndLogsErrorIfNotAuthenticated' for clarity.

[Fact] public async Task ResignInNoOpsAndLogsErrorIfNotAuthenticated()

src/Identity/test/Identity.Test/SignInManagerTest.cs:661

• [nitpick] The test method name 'ResignInNoOpsAndLogsErrorIfAuthenticatedWithDifferentUser' may be misleading since it verifies RefreshSignInAsync behavior; consider renaming it to 'RefreshSignInNoOpsAndLogsErrorIfAuthenticatedWithDifferentUser' for improved clarity.

[Fact] public async Task ResignInNoOpsAndLogsErrorIfAuthenticatedWithDifferentUser()

[hempe]

1. Could you please update the docs for the method as well.
   The current docs do not mention anywhere that the user must already be logged in!
   In the old code, if the user wasn't sign-in, this worked like a normal call to "SignInAsync".

This "patch" broke some edge-cases in our productive environment when azure updated dotnet for our webapps.

Suggested docs:

    /// <summary>
    /// Refresh the sign with the specified <paramref name="user"/>, whilst preserving the existing
    /// AuthenticationProperties of the current signed-in user like rememberMe, as an asynchronous operation.
    /// </summary>
    /// <remarks> User must already be signed in, and user id must match existing user. </remarks>
    /// <param name="user">The user to refresh the sign-in for.</param>
    /// <returns>The task object representing the asynchronous operation.</returns>

2. Useless null checks: on line 180, 181 and 196 you check for auth?.
   But on line 165 you access auth.Succeeded so if auth could be null this would throw already on line 165