Add new rule simple-modifiers

[rmonzon]

Fixes #2863.

Modifiers should have the string as the first param to make things less convoluted and prevent issues with other rules.

Not good:

<div {{(modifier (unless this.hasBeenClicked "track-interaction") "click" customizeData=this.customizeClickData)}}>
  ...
</div>

Good:

<div {{(unless this.hasBeenClicked (modifier "track-interaction" "click" customizeData=this.customizeClickData))}}>
  ...
</div>

[lin-ll]

I think the checks are still mad about the alphabetical order of the rules in the README. Did you use this command to update it? npm run update:readme

[bmish]

Thanks!