WSL: support additional mounts

There are some preparations required:

* the user must be able to sudo mount --all without asking for su password
  add 'youruser ALL=NOPASSWD: /bin/mount, /bin/umount' to /etc/sudoers
* mount points need to be added to /etc/fstab, e.g.
  /mnt/c /c none bind
* mount points need to be created before mounting (e.g. sudo mkdir /c)
* more info: microsoft/WSL#1918 (comment)

wsl/zprofile.zsh

@@ -4,4 +4,6 @@ if [[ -f /proc/version ]] && \
 
   # https://github.com/Microsoft/BashOnWindows/issues/1887
   unsetopt BG_NICE
+
+  sudo mount --all
 fi