[debug] syntax highlight SQL and RQL debug output
This prevent DBG_RQL and DBG_SQL output to looks like a gigantic blob of white
text.
Do this only if we detect that we are in a tty and that pygments is installed.
Closes #17222885
cubicweb source: source-is-missing cubicweb/web/data/jquery.flot.js line length is * characters (>512)