LPS-50696 add a placeholder and change default value

Add a placeholder to make easier for the user to infer the correct
format. Also, don't put a "/" into the field to allow the user to save
an article with an empty value.
LPS-50696 autofill urlTitle and refactor Js code

When the user types a title, autofill automatically with an urlTitle.

Also, make explicit which Js functions are global by using
Liferay.provide.
LPS-50655 give preference to KBArticle object over HTTP parameters

When the portlet is configured to show a folder, it will intialize the
kbArticle to one of the articles inside the folder.
LPS-50655 I know we set STATUS first before ARTICLE in *Portlet, but I think we can retrieve it logically here