If one mod is not signed or broken in any other way, mod.io downloader
fails and does not display any mod.
The problem with unsigned mod is that its metadata are empty.
That means one cannot break mod io downloader with mods having invalid
data.
mark mod as invalid and display in list as disabled and display reason
instead description to not spam ugly error messages on screen as this is
not error by the game but of the moder
report failed signatures back to list of mods
fail if property is not set using strict mode when getting from js
check in js for undefined values
Allow to filter only valid mods.
Differential Revision: https://code.wildfiregames.com/D2114
Reviewed by: @Itms
Fixes: #5459
This was SVN commit r23821.
