Add ability to set button colors individually on Android

android/app/src/main/java/com/reactnativenavigation/params/BaseTitleBarButtonParams.java

     }
 
     private void setColorFromScreenStyle(StyleParams.Color titleBarButtonColor) {
-        if (titleBarButtonColor.hasColor()) {
+        if (titleBarButtonColor.hasColor() && shouldOverrideColorFromScreenStyle()) {
             color = titleBarButtonColor;
         }
     }
 
+    private boolean shouldOverrideColorFromScreenStyle() {
+        // Override color if no color is defined, or if the defined color was set by AppStyle
+        return !color.hasColor() || color == AppStyle.appStyle.titleBarButtonColor;
+    }
+
     public StyleParams.Color getColor() {
         if (enabled) {
             return color;

src/deprecated/platformSpecificDeprecated.android.js

           button.icon = icon.uri;
         }
       }
+      if (button.buttonColor) {
+        button.color = processColor(button.buttonColor);
+      }
     });
   }
   let leftButton = getLeftButton(params);
         leftButton.icon = icon.uri;
       }
     }
+    if (leftButton.buttonColor) {
+      leftButton.color = processColor(leftButton.buttonColor);
+    }
   } else if (shouldRemoveLeftButton(params)) {
     leftButton = {};
   }
           button.icon = icon.uri;
         }
       }
+      if (button.buttonColor) {
+        button.color = processColor(button.buttonColor);
+      }
     });
   }
 
         leftButton.icon = icon.uri;
       }
     }
+    if (leftButton.buttonColor) {
+      leftButton.color = processColor(leftButton.buttonColor);
+    }
   }
 
   const fab = getFab(screen);