add FAVORITE_EMPTY icon (hollow star) (#130)

Author: Eldrinn-Elantey

src/main/java/com/cleanroommc/modularui/drawable/GuiTextures.java

@@ -73,6 +73,7 @@ public interface GuiTextures {
     UITexture SOUND = icon("sound", 144, 48);
     UITexture SEARCH = icon("search", 160, 48);
     UITexture CHECKMARK = icon("checkmark", 176, 48);
+    UITexture FAVORITE_EMPTY = icon("favorite_empty", 192, 48);
 
     UITexture CHECKBOARD = icon("checkboard", 0, 240);
     UITexture DISABLED = icon("disabled", 16, 240);