refactor: Calc avatar font size by avatar size

lib/widgets/avatar.dart

@@ -13,7 +13,6 @@ class Avatar extends StatelessWidget {
   final void Function()? onTap;
   static const double defaultSize = 44;
   final Client? client;
-  final double fontSize;
   final String? presenceUserId;
   final Color? presenceBackgroundColor;
 
@@ -23,7 +22,6 @@ class Avatar extends StatelessWidget {
     this.size = defaultSize,
     this.onTap,
     this.client,
-    this.fontSize = 18,
     this.presenceUserId,
     this.presenceBackgroundColor,
     super.key,
@@ -48,7 +46,7 @@ class Avatar extends StatelessWidget {
         fallbackLetters,
         style: TextStyle(
           color: noPic ? Colors.white : null,
-          fontSize: fontSize,
+          fontSize: (size / 2.5).roundToDouble(),
         ),
       ),
     );

lib/widgets/public_room_bottom_sheet.dart

@@ -133,7 +133,6 @@ class PublicRoomBottomSheet extends StatelessWidget {
                         mxContent: profile.avatarUrl,
                         name: profile.name ?? roomAlias,
                         size: Avatar.defaultSize * 3,
-                        fontSize: 36,
                       ),
                     ),
                   ),