bpo-39791: Add files() to importlib.resources (GH-19722)

* bpo-39791: Update importlib.resources to support files() API (importlib_resources 1.5).

* 📜🤖 Added by blurb_it.

* Add some documentation about the new objects added.

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Lib/test/test_importlib/test_files.py

@@ -0,0 +1,39 @@
+import typing
+import unittest
+
+from importlib import resources
+from importlib.abc import Traversable
+from . import data01
+from . import util
+
+
+class FilesTests:
+    def test_read_bytes(self):
+        files = resources.files(self.data)
+        actual = files.joinpath('utf-8.file').read_bytes()
+        assert actual == b'Hello, UTF-8 world!\n'
+
+    def test_read_text(self):
+        files = resources.files(self.data)
+        actual = files.joinpath('utf-8.file').read_text()
+        assert actual == 'Hello, UTF-8 world!\n'
+
+    @unittest.skipUnless(
+        hasattr(typing, 'runtime_checkable'),
+        "Only suitable when typing supports runtime_checkable",
+        )
+    def test_traversable(self):
+        assert isinstance(resources.files(self.data), Traversable)
+
+
+class OpenDiskTests(FilesTests, unittest.TestCase):
+    def setUp(self):
+        self.data = data01
+
+
+class OpenZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
+    pass
+
+
+if __name__ == '__main__':
+    unittest.main()