[TIDOC-1113] Rework Header code to support not using a drop-down menu

TESTING:

Run deploy and clouddeploy scripts.  Drop-down menu and button should appear the same as the production site.

In the doctools parent directory, remove the `--body-html` option from the `jsduck.config` and `jsduck_cloud.config` files.  Rerun the deploy and clouddeploy scripts.  A label should replace the drop-down menu and button, and the cursor should not change when hovering over the label.