Added the function to check class information

Added the function to check class information on the stats screen. This can be accessed by pressing the start button on the upper screen.

It displays the class rank, crit bonus, and destinations of the promotion from the current class.

Up to 3 promotion destinations will be displayed
Example of when both crit bonus and promotion destinations are displayed
Example of a case where the unit has no promotion destinations
The promotion is only displayed for allied units.
Promotions by events and changing class by Porter Proof are not included in this display.