make xdg-desktop-portal-cosmic path non fixed to libexec

[Keloran]

arch and other dists dont use libexec

[Drakulix]

This now instead just hard codes two paths. Please make this build-time configurable (e.g. via an env-variable), like we do in other projects instead.

[Keloran]

Moved to env setting hopefully did "COSMIC_DESKTOP_PORTAL" as the env setting, hopefully is an acceptable name

[ryanabx]

This is semi-related to this PR as well pop-os/launcher#242 , which is also setting an environment variable to use something different than the default (in launcher the current default is lib)

[Conan-Kudo]

Yeah, I mentioned in there we should default to libexec there since nearly all distributions use it, and those that don't can override it accordingly.

[Keloran]

This now instead just hard codes two paths. Please make this build-time configurable (e.g. via an env-variable), like we do in other projects instead.

is this change more what you were after ?