Inline boundaries don't work properly when using multiple inline formats

[youknowriad]

Describe the bug

I have the following content in my post

<!-- wp:paragraph -->
<p><em>italic <code>code</code></em></p>
<!-- /wp:paragraph -->

Notice that it's impossible to move the caret after the code element, but before still inside the em to continue typing italic text.

Expected behavior
I expected the first right arrow key presse to go out of the code element but stay inside the em and the second one to go out of the em

[ellatrix]

I wonder if this is an issue in TinyMCE inline mode as well. In any case, this will be resolved by #11322. Seems like I should prioritise that PR soon.