Add iterator of raw dependencie (Requires-Dist) to BaseDistribution

Author: sbidoul

src/pip/_internal/metadata/base.py

@@ -445,6 +445,10 @@ def iter_dependencies(self, extras: Collection[str] = ()) -> Iterable[Requiremen
         """
         raise NotImplementedError()
 
+    def iter_raw_dependencies(self) -> Iterable[str]:
+        """Raw Requires-Dist metadata."""
+        return self.metadata.get_all("Requires-Dist", [])
+
     def iter_provided_extras(self) -> Iterable[NormalizedName]:
         """Extras provided by this distribution.