feat: add {module} as a magic string for the afterModule setting

[wkillerud]

This should fix an issue seen in SublimeText where the editor would replace the module itself (eg module.$variable, module end up as .$variable).

To use it, apply this setting:

{
  "settings": {
    "somesass": {
      "completion": {
        "afterModule": "{module}"
      }
    }
  }
}