Prevent inaccessible links from being displayed in LinkFormatter

republishing after discussion that this can be handled in public.

MR created (PS: Nightwatch tests seem unstable, I had to re-run).

Please check #4 and #13, I feel like this issue extends beyond link formatters so leaving to needs work...
Here is a static patch from MR for composer.

Rebased and moving to review, to get feedback on the approach, thanks.

Left some comments on MR.

Thanks, though I wasn't looking for a code review yet (tests and upgrade path still todo) but rather opinions on the overall approach / scope as it may extend way beyond link formatters.
See #13.