title: Annotate left side of facet_grid using tag_facet_outside?
body: <p>Am following a very similar query to <a href="https://stackoverflow.com/questions/11889625/annotating-text-on-individual-facet-in-ggplot2">this previous question</a> and answer from @Tung, where I'd like to annotate a facet_grid using letters on the outside of the plot. The wonderful <code>egg::tag_facet_outside</code> function is kind of what I'm after...</p>
  <pre><code>library(ggplot2)
  
  p &lt;- ggplot(mtcars, aes(qsec, mpg)) + 
    geom_point() + 
    facet_grid(cyl ~ am, switch = 'y') +
    theme_bw(base_size = 12) +
    theme(strip.placement = 'outside')
  
  library(egg)
  tag_facet_outside(p)
  </code></pre>
  <p>Which yields this...</p>
  <p><a href="https://i.stack.imgur.com/eZZ9P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eZZ9P.png" alt="enter image description here" /></a></p>
  <p>My question is whether I can shift the roman numeral labels that are currently on the <strong>right</strong> hand side of the graph to the <strong>left</strong> hand side? Within tag_facet_outside() there is the option to specify parameters for <code>tag_fun_right=</code> as well as options of specifying coordinates but I just can't seem to get these labels to appear all the way over to the left.</p>
  <p>Next one is - is it possible to remove the top row of tags altogether, possibly by specifying the <code>tag_fun_top</code> ?
  Any help appreciated! Thanks</p>