Refactor color management and UI components for consistency

- Updated color references in various widgets to use the new `opaquePrimary` color for better visual consistency.
- Refactored `ColorsManager` to improve color definitions and removed redundant color declarations.
- Enhanced UI elements across multiple dialogs and widgets to ensure a cohesive design language.

This change promotes maintainability and aligns with the updated color scheme.

lib/pages/roles_and_permission/view/role_card.dart

@@ -9,7 +9,7 @@ class RoleCard extends StatelessWidget {
   Widget build(BuildContext context) {
     return Container(
       decoration: BoxDecoration(
-        color: ColorsManager.whiteColors, // Card background color
+        color: ColorsManager.white, // Card background color
         borderRadius: BorderRadius.circular(20), // Rounded corners
         boxShadow: [
           BoxShadow(
@@ -22,8 +22,8 @@ class RoleCard extends StatelessWidget {
       ),
       child: Container(
         decoration: BoxDecoration(
-          color: ColorsManager.whiteColors,
-          borderRadius: BorderRadius.circular(20), 
+          color: ColorsManager.white,
+          borderRadius: BorderRadius.circular(20),
         ),
         child: Column(
           mainAxisAlignment: MainAxisAlignment.spaceEvenly,