analyze-snap should better identify running things through snap run

When a user has both a deb and a snap installed, i.e. has the following setup:

```
$  which -a vlc
/usr/bin/vlc
/bin/vlc
/snap/bin/vlc
```

etrace should do the right thing and figure out that since there are variants of the snap on $PATH that are not actually a snap, we need to pass explicitly `--use-snap-run` too.