[FIX] markdown : prevent markdown table to be broken by plugins

It has been noticed that when converting a page with wiki syntax to markdown, the conversion succeeds but the markdown table is not well supported. So we took the time to first analyze the conversion step if a process was the cause of the malfunction but at the time of the conversion everything went well without any problem. So after several tests we noticed there is some plugin, which was originally implemented to support wiki syntax, which means that when we do this conversion, certain markdown characters will be interpreted as wiki syntax by the wiki plugin. As for the markdown table, the plugin manages the indentation according to wiki syntax, which does not correspond to that of the markdown which has its own indentation. To be fixed it required to escape during conversion to prevent plugins or third party to broke the the table. Related task : https://avan.tech/item90013-Markdown-conversion-Some-tables-broken