_migrationsAssemblyObject is missing from RelationalOptionsExtension copy constructor

[Copilot]

• Identify the issue in RelationalOptionsExtension copy constructor where _migrationsAssemblyObject is not being copied
• Create a test to verify the issue and add it to RelationalOptionsExtensionTest class
• Create a separate test program to verify the issue reproduction and the fix
• Implement the fix by adding the missing assignment in the copy constructor: _migrationsAssemblyObject = copyFrom._migrationsAssemblyObject;
• Verify that the fix works with both test approaches

This PR fixes an issue where the _migrationsAssemblyObject field was not being copied in the RelationalOptionsExtension copy constructor. This caused the migrations assembly object to be lost if any other configuration method was called after MigrationsAssembly(Assembly), requiring users to call this method last in their configuration chain.

Fixes #36053.

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[Copilot]

Pull Request Overview

This PR addresses an issue in the RelationalOptionsExtension copy constructor where the _migrationsAssemblyObject field was not being copied and verifies the fix with an added test.

• Added a test to ensure that the migrations assembly object is preserved after cloning.
• Fixed the copy constructor in RelationalOptionsExtension to correctly assign _migrationsAssemblyObject.

Reviewed Changes

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

File	Description
test/EFCore.Relational.Tests/Infrastructure/RelationalOptionsExtensionTest.cs	Added test verifying migrations assembly object preservation after cloning.
src/EFCore.Relational/Infrastructure/RelationalOptionsExtension.cs	Fixed missing assignment of _migrationsAssemblyObject in the copy constructor.