design: Use more adaptive elements

This uses iOS styled Sliders and share
icons on iOS.

lib/pages/chat/events/audio_player.dart

@@ -173,7 +173,7 @@ class _AudioPlayerState extends State<AudioPlayerWidget> {
                   ),
           ),
           Expanded(
-            child: Slider(
+            child: Slider.adaptive(
               activeColor: Theme.of(context).colorScheme.secondaryVariant,
               inactiveColor: widget.color.withAlpha(64),
               value: currentPosition,

lib/pages/chat_details/chat_details_view.dart

@@ -66,7 +66,7 @@ class ChatDetailsView extends StatelessWidget {
                     if (room.canonicalAlias?.isNotEmpty ?? false)
                       IconButton(
                         tooltip: L10n.of(context).share,
-                        icon: const Icon(Icons.share_outlined),
+                        icon: Icon(Icons.adaptive.share_outlined),
                         onPressed: () => FluffyShare.share(
                             AppConfig.inviteLinkPrefix + room.canonicalAlias,
                             context),

lib/pages/settings_style/settings_style_view.dart

@@ -140,7 +140,7 @@ class SettingsStyleView extends StatelessWidget {
                 ),
               ),
             ),
-            Slider(
+            Slider.adaptive(
               min: 0.5,
               max: 2.5,
               divisions: 20,

lib/pages/user_bottom_sheet/user_bottom_sheet_view.dart

@@ -119,7 +119,7 @@ class UserBottomSheetView extends StatelessWidget {
                   ListTile(
                     title: Text(L10n.of(context).username),
                     subtitle: Text(user.id),
-                    trailing: const Icon(Icons.share_outlined),
+                    trailing: Icon(Icons.adaptive.share_outlined),
                     onTap: () => FluffyShare.share(
                         user.id, controller.widget.outerContext),
                   ),