Scripts fixes and improvements

- ensure all scripts use $NVBASE $MAGISKBIN $POSTFSDATAD and $SERVICED where appropriate
- simplify new grep_cmdline() using xargs and more sed
- show correct active sepolicy $RULESDIR on devices with no encryption
- add support for Android 12 .capex (compressed apex) files

app/src/main/res/raw/manager.sh

@@ -91,7 +91,7 @@ restore_imgs() {
 }
 
 post_ota() {
-  cd /data/adb
+  cd $NVBASE
   cp -f $1 bootctl
   rm -f $1
   chmod 755 bootctl