Add JIRA macro converter

The JIRA macro in XWiki and Confluence use the same `jira` keyword*, but otherwise use a different format. The Jira server is specified in the `id` parameter (set through the Jira Administration macro) in XWiki, while it is specified in the `server` parameter in Confluence. The issues to list or JQL query to execute are specified in the macro body in XWiki while they are specified in parameters in Confluence. A macro converter could be created to automatically convert the Confluence macro format to the XWiki format.

Macro documentations:

https://confluence.atlassian.com/doc/jira-issues-macro-139380.html *

https://extensions.xwiki.org/xwiki/bin/view/Extension/JIRA%20Macro

https://extensions.xwiki.org/xwiki/bin/view/Extension/JIRA%20Administration/

• The Confluence documentation states that the macro name/keyword is `jiraissues`. In our version of Confluence (7.4.4) however, the macro is inserted with the keyword `jira`.