ABRepeatView: Add AB Repeat feature

This merge request adds the AB Repeat feature to the players.

The user can setup two marks in order to create a loop in the currently playing media.

The user is also able to reset the marks in order to replace them or totaly remove the loop once one is setup.

Screenshots of the AB Repeat feature

This merge request also brings some adjustments to:

• The brightness and volume sliders of the players that now do not overlap the OptionsNavigationBar anymore.
• The OptionsNavigationBar icons' aspect ratio that is now preserved by setting the content mode to .scaleAspectFit.

Here are some screenshots displaying the overlapping issue

Closes #848 (closed)

Credits for the ABRepeat icons: @Corbax

Resources/en.lproj/Localizable.strings

@@ -455,6 +455,12 @@
 
 "INTERFACE_LOCK_BUTTON" = "Lock interface";
 
+"AB_LOOP" = "A→B Loop";
+"AB_LOOP_MARKS" = "A→B Loop Marks";
+
+"RESET_AB_LOOP" = "Do you want to remove the A→B loop?";
+"RESET_AB_LOOP_MARKS" = "Do you want to reset the A→B loop marks?";
+
 "SHUFFLE_HINT" = "Shuffle media list";
 "SHUFFLE_OFF_HINT" = "Do not shuffle media list";