Making tinyMCE use the safe_html filter configuration

As we know the safe_html does filtering on server side and tinyMCE works on client side and as the tinyMCE has its own filter criteria so there may be differences in the filtering for the text from safe_html and tinyMCE so we will try to configure tinyMCE according to safe_html so to match the filter criteria between them and also the filter criteria will match both at server and client.

The issue concerns matching tinyMCE's client-side filtering with the safe_html server-side filter, but it names no files, tests, or entry points. Start by locating the tinyMCE configuration and safe_html filter implementation; done means their allowed filtering criteria are aligned and the behavior is verified on both sides.

Written by the indexing model from the issue text.