Don't offer to reference the target project when adding a project reference

[dawedawe]

WHAT

🤖 Generated by Copilot at becb165

Fixed a bug and improved the user experience for adding project references in FsProjEdit.fs. Filtered out the current project and handled None paths in addProjectReferencePath.

🤖 Generated by Copilot at becb165

addProjectReferencePath Filters out self, handles None Autumn bug fixing

🐛🚸🔧

WHY

Don't offer people a rope.

HOW

🤖 Generated by Copilot at becb165

• Fix a bug that allowed adding a circular reference to the same project and improve the user experience by showing only relevant options (link)