Fix crash with info inset and dialogs

Fix crash with info inset and dialogs

See the thread
  2.4 Crash (was: Updated LaTeXConfig.lyx (bxjsclasses added))
on lyx-devel (26/01/2023).

The backtrace imply a problem like:
1/ metrics are computed for some info inset
2/ the info inset is regenerated (and thus the paragraph it held is now invalid)
3/ We draw the inset and because of the new (disabled by default)
   bookmark display code, we access the id() of the invalid paragraph.
4/ boom!

To fix the issue, introduce a new boolean member that indicates when
the Row object of the metrics should not be used. In this case, the
draw() method returns early.