title: Can ggplot titles contain line breaks (when used with ggtext)?
body: <pre><code>library(tidyverse)
  library(ggtext)
  ggplot(mpg, aes(cty, hwy)) + 
    geom_point() + 
    labs(title = "This is a Title\n") +
    theme(plot.title.position = "plot",
          plot.title = element_markdown(), 
          legend.position = "none")
  </code></pre>
  
  <p>Why can't I add a line break to my ggplot title to get some white space between the title and panel? I know there's other ways to achieve this padding, but I want to limit this question explicitly to line break methods for adding white space.</p>
  
  <p>I'm almost certain I've done this before for axis titles to add white space between the axis title and plot panel. Why won't <code>\n</code> work in the plot title?</p>
  
  <p><a href="https://i.stack.imgur.com/XNIhv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XNIhv.png" alt="enter image description here"></a></p>
  
  <hr>
  
  <p><em>Edit with additional information based on comments</em></p>
  
  <p>This code chunk will break a title into two lines.</p>
  
  <pre><code>ggplot(mpg, aes(cty, hwy)) +
    geom_point() +
    labs(title = "Line Number One\nLine Number Two") +
    theme(plot.title.position = "plot",
          legend.position = "none")
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/wRW5R.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wRW5R.png" alt="enter image description here"></a></p>
  
  <p>This "almost identical" code chunk won't. The big question... <strong>Why?</strong> I imagine in Markdown I need the <code>&lt;br&gt;</code> or maybe two spaces? to break the line?</p>
  
  <pre><code>ggplot(mpg, aes(cty, hwy)) + 
    geom_point() + 
    labs(title = "The First Line\nThe Second Line") +
    theme(plot.title.position = "plot",
          plot.title = element_markdown(), 
          legend.position = "none")
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/BDunN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BDunN.png" alt="enter image description here"></a></p>