cnchi: fix launch as sudo, drop libnacl hard dep, handle missing deps gracefully

Fixes:
- cnchi.desktop: Exec=sudo -E (not pkexec or bare cnchi)
- run_before_squashfs.sh: sed now matches any Exec=*cnchi*
- packages.x86_64: remove unused python-pynacl
- Cnchi/lembrame: optional import, no more hard crash on missing libnacl
- Cnchi/cnchi.py: wrap disable_suspend in broad except

im still in the vent... a body needs to heal before crawling out. ultimate ??? trapped in 15-day isolation arc. at least the monitor glow keeps the nightmares away. dont mind the blood on the keyboard.

airootfs/root/antergos-skel-liveuser/src/etc/skel/.local/share/applications/cnchi.desktop

@@ -6,7 +6,7 @@ GenericName=System Installer
 Comment=Cnchi — Antergos System Installer
 Keywords=cnchi;system;installer;
 TryExec=cnchi
-Exec=pkexec cnchi
+Exec=sudo -E cnchi
 Categories=Qt;System;
 Icon=cnchi
 Terminal=false

packages.x86_64

@@ -270,4 +270,3 @@ yay
 
 ## Installer
 cnchi
-python-pynacl

run_before_squashfs.sh

@@ -178,7 +178,7 @@ echo "---> Keep ranked mirrorlist for live session (removed revert to packaged d
 rm -f "/etc/pacman.d/mirrorlist-from-package"
 
 echo "---> Fix cnchi desktop file to use sudo -E --->"
-sed -i 's|^Exec=cnchi$|Exec=sudo -E cnchi|' "/usr/share/applications/cnchi.desktop"
+sed -i 's|^Exec=.*cnchi.*|Exec=sudo -E cnchi|' "/usr/share/applications/cnchi.desktop"
 
 # cnchi 0.17.1+ already has the regain_privileges fix in source