python,runfiles: move to different package

Move the Python runfiles library from
`@bazel_tools//tools/runfiles:py-runfiles` to
`@bazel_tools//tools/python/runfiles:runfiles`

Also rename the testdata runfiles.py to foo.py.
This file was not a mock runfiles library, just a
client file using the runfiles library that was
also called runfiles.py

Fixes https://github.com/bazelbuild/bazel/issues/4878

Change-Id: I874b230c93679d4454ac91e816932c8272ecc5c7

Closes #4981.

Change-Id: I908e0ab7ec61225e82f70793b1a05432e7f0b07e
PiperOrigin-RevId: 192256481
diff --git a/tools/python/BUILD b/tools/python/BUILD
index 6933f9d..ab09128 100644
--- a/tools/python/BUILD
+++ b/tools/python/BUILD
@@ -6,10 +6,28 @@
 )
 
 filegroup(
-    name = "srcs",
+    name = "srcs_and_embedded_tools",
     srcs = [
         # Tools are build from the workspace for tests.
         "2to3.sh",
         "BUILD",
     ],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "srcs",
+    srcs = [
+        ":srcs_and_embedded_tools",
+        "//tools/python/runfiles:srcs",
+    ],
+)
+
+filegroup(
+    name = "embedded_tools",
+    srcs = [
+        ":srcs_and_embedded_tools",
+        "//tools/python/runfiles:embedded_tools",
+    ],
+    visibility = ["//tools:__pkg__"],
 )