♻️ Fix epub reader ugliness

[aaronleopold]

Relates to https://github.com/stumpapp/stump/issues/179

• Updated the UI for the epub-js reader
• Added support for both ltr and rtl reading directions
• Added support for toggling theme directly from reader
• Updated the font size form

I didn't get to test using some sort of read out loud feature, but I will try to get to that soon