Move the three regression test cases for issue #1370 from _cmptest/ to _demo/:
- issue1370_gotypes (go/types.Object test)
- issue1370_goast (go/ast.Expr test)
- issue1370_geometry (custom interface test)
Updated import path in geometry.go to reflect new location.
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Co-authored-by: luoliwoshang <51194195+luoliwoshang@users.noreply.github.com>