This does two things related to search paths:
- also search for webapp symlink in the case of packaged applications
(e.g. Archlinux used to provide a symlink this way, linking to a
riot-web copy installed elsewhere, instead of creating an asar of it)
- also take dirname(asarPath) as a valid resources path, as this is how
riot-desktop currently is packaged. Fixesvector-im/riot-web#13190.