Docs: Make docsite rebuilds smarter/faster (#45062)

* Make the following scripts  idempotent so that we only have to rebuild changed docs, not all docs:

  * plugin_formatter
  * generate_man
  * dump_keywords.py
  * dump_config.py
  * testing_formatter.sh

docs/bin/testing_formatter.sh

@@ -1,6 +1,8 @@
 #!/bin/bash -eu
 
-cat <<- EOF > ../docsite/rst/dev_guide/testing/sanity/index.rst
+FILENAME=../docsite/rst/dev_guide/testing/sanity/index.rst
+
+cat <<- EOF >$FILENAME.new
 Sanity Tests
 ============
 
@@ -12,5 +14,9 @@ This list is also available using \`\`ansible-test sanity --list-tests\`\`.
 
 $(for test in $(../../test/runner/ansible-test sanity --list-tests); do echo "   ${test}"; done)
 
-
 EOF
+
+# Put file into place if it has changed
+if [ "$(sha1sum <$FILENAME)" != "$(sha1sum <$FILENAME.new)" ]; then
+    mv -f $FILENAME.new $FILENAME
+fi