Revert "Remove importlib-metadata and importlib-resources"

This reverts commit 38435ae81c.

lib/importlib_metadata/_py39compat.py

@@ -0,0 +1,35 @@
+"""
+Compatibility layer with Python 3.8/3.9
+"""
+from typing import TYPE_CHECKING, Any, Optional
+
+if TYPE_CHECKING:  # pragma: no cover
+    # Prevent circular imports on runtime.
+    from . import Distribution, EntryPoint
+else:
+    Distribution = EntryPoint = Any
+
+
+def normalized_name(dist: Distribution) -> Optional[str]:
+    """
+    Honor name normalization for distributions that don't provide ``_normalized_name``.
+    """
+    try:
+        return dist._normalized_name
+    except AttributeError:
+        from . import Prepared  # -> delay to prevent circular imports.
+
+        return Prepared.normalize(getattr(dist, "name", None) or dist.metadata['Name'])
+
+
+def ep_matches(ep: EntryPoint, **params) -> bool:
+    """
+    Workaround for ``EntryPoint`` objects without the ``matches`` method.
+    """
+    try:
+        return ep.matches(**params)
+    except AttributeError:
+        from . import EntryPoint  # -> delay to prevent circular imports.
+
+        # Reconstruct the EntryPoint object to make sure it is compatible.
+        return EntryPoint(ep.name, ep.value, ep.group).matches(**params)