Allow disabling anti-aliasing via a setting (#241)

## Summary

Fixes https://github.com/daveallie/crosspoint-reader/issues/233

## Additional Context

By disabling the Text Anti-Aliasing in the settings, you can get faster
black-and-white page turns that work exactly like the stock firmware,
instead of having an additional flash after rendering (see issue linked
above for example).

Tested on the X4 and confirmed working.

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

src/activities/reader/EpubReaderActivity.cpp

@@ -388,7 +388,7 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
 
   // grayscale rendering
   // TODO: Only do this if font supports it
-  {
+  if (SETTINGS.textAntiAliasing) {
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_LSB);
     page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);