fix: missing binary in activation script

[DaRacci]

Had an issue when moving some directories over to symlink after being bindfs mounts, encountered this error on my next home-manager activation.

This patch should ensure that fusermount is not missing by referencing a binary within the store.

Log:

warning: the following units failed: home-manager-racci.service
× home-manager-racci.service - Home Manager environment for racci
     Loaded: loaded (/etc/systemd/system/home-manager-racci.service; enabled; preset: ignored)
     Active: failed (Result: exit-code) since Tue 2024-12-31 18:34:36 AEDT; 260ms ago
 Invocation: 93b46f796df94e409da03faadbe01b38
    Process: 1562829 ExecStart=/nix/store/m91h9kmjw78swvldfb9px8qnv1nb23ax-hm-setup-env /nix/store/lshgw95gk6rkyaw5kq3rcypq3g9rrj72-home-manager-generation (code=exited, status=127)
   Main PID: 1562829 (code=exited, status=127)
         IP: 0B in, 0B out
         IO: 64K read, 0B written
   Mem peak: 6.4M
        CPU: 83ms

Dec 31 18:34:34 nixe hm-activate-racci[1562829]: Activating checkFilesChanged
Dec 31 18:34:34 nixe hm-activate-racci[1562829]: Activating cleanEmptyLinkTargets
Dec 31 18:34:34 nixe hm-activate-racci[1562895]: /nix/store/lshgw95gk6rkyaw5kq3rcypq3g9rrj72-home-manager-generation/activate: line 250: fusermount: command not found
Dec 31 18:34:35 nixe hm-activate-racci[1563086]: /nix/store/lshgw95gk6rkyaw5kq3rcypq3g9rrj72-home-manager-generation/activate: line 250: fusermount: command not found
Dec 31 18:34:36 nixe hm-activate-racci[1563088]: /nix/store/lshgw95gk6rkyaw5kq3rcypq3g9rrj72-home-manager-generation/activate: line 250: fusermount: command not found
Dec 31 18:34:36 nixe hm-activate-racci[1562829]: Couldn't perform regular unmount of /home/racci/.config/Nextcloud. Attempting lazy unmount.
Dec 31 18:34:36 nixe hm-activate-racci[1563089]: /nix/store/lshgw95gk6rkyaw5kq3rcypq3g9rrj72-home-manager-generation/activate: line 256: fusermount: command not found
Dec 31 18:34:36 nixe systemd[1]: home-manager-racci.service: Main process exited, code=exited, status=127/n/a
Dec 31 18:34:36 nixe systemd[1]: home-manager-racci.service: Failed with result 'exit-code'.
Dec 31 18:34:36 nixe systemd[1]: Failed to start Home Manager environment for racci.
warning: error(s) occurred while switching to the new configuration