Handling of Duplicate References in Solution Files

[v-wuzhai]

Describe the bug

The current behavior is that when duplicate references are present in solution files, vs-solutionpersistence removes all these duplicate references. This behavior can lead to unexpected results and management confusion.

Current Behavior：When duplicate project references are present in solution files, all duplicate references are automatically removed. This causes the test WhenDuplicateReferencesArePresentItRemovesThemAll to fail.

Expected Behavior

Should be able to recognize and handle duplicate references, or provide a clear error message indicating the presence of duplicate references, rather than simply removing them.

[edvilme]

I can look into this, but I think this is more of a vs-solutionpersistence issue, we could maybe give a warning?