Add paragraph alignment setting (justify/left/center/right) (#191)

## Summary

* **What is the goal of this PR?** 

Add a new user setting for paragraph alignment, instead of hard-coding
full justification.

* **What changes are included?**

One new line in the settings screen, with 4 options
(justify/left/center/right). Default is justified since that's what it
was already. I personally only wanted to disable justification and use
"left", but I included the other options for completeness since they
were already supported.

## Additional Context

Tested on my X4 and looks as expected for each alignment.

Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>

src/activities/reader/EpubReaderActivity.cpp

@@ -267,7 +267,8 @@ void EpubReaderActivity::renderScreen() {
     const uint16_t viewportHeight = renderer.getScreenHeight() - orientedMarginTop - orientedMarginBottom;
 
     if (!section->loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
-                                  SETTINGS.extraParagraphSpacing, viewportWidth, viewportHeight)) {
+                                  SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
+                                  viewportHeight)) {
       Serial.printf("[%lu] [ERS] Cache not found, building...\n", millis());
 
       // Progress bar dimensions
@@ -311,8 +312,8 @@ void EpubReaderActivity::renderScreen() {
       };
 
       if (!section->createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
-                                      SETTINGS.extraParagraphSpacing, viewportWidth, viewportHeight, progressSetup,
-                                      progressCallback)) {
+                                      SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
+                                      viewportHeight, progressSetup, progressCallback)) {
         Serial.printf("[%lu] [ERS] Failed to persist page data to SD\n", millis());
         section.reset();
         return;