chore: rename the dev-only setup files to more clearly self-describe what they are (#2436)

The names `internal_deps` and `internal_setup` are a bit confusing and
ambiguous: are they
for setting up something internal so that rules_python works, or
something else?

Clarify by putting `dev` in their names. This helps match the naming
used for bzlmod
(python/private/internal_dev_deps.bzl).

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 46ebbc8..f03cc26 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -17,7 +17,7 @@
 # Everything below this line is used only for developing rules_python. Users
 # should not copy it to their WORKSPACE.
 
-load("//:internal_deps.bzl", "rules_python_internal_deps")
+load("//:internal_dev_deps.bzl", "rules_python_internal_deps")
 
 rules_python_internal_deps()
 
@@ -37,7 +37,7 @@
 
 stardoc_pinned_maven_install()
 
-load("//:internal_setup.bzl", "rules_python_internal_setup")
+load("//:internal_dev_setup.bzl", "rules_python_internal_setup")
 
 rules_python_internal_setup()