Should Throw Error When Adding Projects with the Same Name but Different Paths to Solution Folder

[v-wuzhai]

Describe the bug

The current behavior allows these projects to be added to the same solution folder, which can lead to naming conflicts and management confusion.

Current Behavior：When attempting to add projects with the same name but different paths to a solution folder, this operation is allowed and does not throw an error. This causes the test WhenNestedDuplicateProjectIsAddedToASolutionFolder to fail.

Expected Behavior

An error should be thrown in this scenario, indicating a naming conflict and preventing the addition. This will ensure the correctness and consistency of the project.

[dotnet-issue-labeler]

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[dotnet-issue-labeler]

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