Bazel: stub internal repo parts needed for building rust binaries

This is another shot at github#17382,
using a different and more lightweight approach.

This allows building the ruby and python (and in the future also rust)
packs from within the codeql repository. This will:
* skip defining the glibc symbols checking, which only makes sense when
  building the release from the internal repository
* stub out our `universal_binary` rule, which we only need when building
  the release.

Author: Paolo Tranquilli

misc/bazel/rust.bzl

@@ -8,7 +8,7 @@ def codeql_rust_binary(
         visibility = None,
         symbols_test = True,
         **kwargs):
-    rust_label_name = name + "_single_arch"
+    rust_label_name = "single_arch/" + name
     universal_binary(
         name = name,
         dep = ":" + rust_label_name,