rules_pip: update to new version

rules_pip has a new version [1] of their rule system, incompatible with the
version we used, that fixes a bunch of issues, notably:
 - explicit tagging of repositories for PY2/PY3/PY23 support
 - removal of dependency on host pip (in exchange for having to vendor
   wheels)
 - higher quality tooling for locking

We update to the newer version of pip_rules, rename the external
repository to pydeps and move requirements.txt, the lockfile and the
newly vendored wheels to third_party/, where they belong.

[1] - https://github.com/apt-itude/rules_pip/issues/16

Change-Id: I1065ee2fc410e52fca2be89fcbdd4cc5a4755d55
diff --git a/bgpwtf/cccampix/frontend/BUILD.bazel b/bgpwtf/cccampix/frontend/BUILD.bazel
index 9b14017..6fae1d3 100644
--- a/bgpwtf/cccampix/frontend/BUILD.bazel
+++ b/bgpwtf/cccampix/frontend/BUILD.bazel
@@ -10,9 +10,9 @@
         "templates/**",
     ]),
     deps = [
-        "@pip36//arrow",
-        "@pip36//flask",
-        "@pip36//grpcio",
+        "@pydeps//arrow",
+        "@pydeps//flask",
+        "@pydeps//grpcio",
         "//bgpwtf/cccampix/proto:ix_py_proto",
     ],
 )
@@ -36,8 +36,8 @@
     ],
     deps = [
         ":frontend_lib",
-        "@pip36//gevent",
-        "@pip36//gunicorn",
+        "@pydeps//gevent",
+        "@pydeps//gunicorn",
     ],
     visibility = [
         "//bgpwtf/cccampix:__pkg__",