Add empty-init code-smell script. (#18406)

Also removed boilerplate from otherwise empty __init__.py files
which should not contain any code (checked by empty-init script).

test/sanity/code-smell/boilerplate.sh

@@ -4,6 +4,7 @@ metaclass1=$(find ./bin -type f -exec grep -HL '__metaclass__ = type' \{\} \; )
 future1=$(find ./bin -type f -exec grep -HL 'from __future__ import (absolute_import, division, print_function)' \{\} \;)
 
 metaclass2=$(find ./lib/ansible -path ./lib/ansible/modules/core -prune \
+        -o -path ./lib/ansible/modules/__init__.py \
         -o -path ./lib/ansible/modules/extras -prune \
         -o -path ./lib/ansible/module_utils -prune \
         -o -path ./lib/ansible/compat/six/_six.py -prune \
@@ -11,6 +12,7 @@ metaclass2=$(find ./lib/ansible -path ./lib/ansible/modules/core -prune \
         -o -name '*.py' -exec grep -HL '__metaclass__ = type' \{\} \;)
 
 future2=$(find ./lib/ansible -path ./lib/ansible/modules/core -prune \
+        -o -path ./lib/ansible/modules/__init__.py \
         -o -path ./lib/ansible/modules/extras -prune \
         -o -path ./lib/ansible/module_utils -prune \
         -o -path ./lib/ansible/compat/six/_six.py -prune \

test/sanity/code-smell/empty-init.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+found=''
+
+for path in lib/ansible/modules/ test/units/; do
+    files=$(find "${path}" -name __init__.py -size '+0')
+
+    if [ "${files}" ]; then
+        echo "${files}"
+        found=1
+    fi
+done
+
+if [ "${found}" ]; then
+    echo "One or more __init__.py file(s) listed above are non-empty."
+    exit 1
+fi