chore(mobile): reduce spacing on video controls (#27313)

The spacing was required for the old slider, but the new one has its own
spacing and makes it redundant. There is too much now, and we've
received feedback that it should be less sparse. The default track
height of 16px is an improvement over the old track height, but it is
very thick. A middleground of 12px might be better.

mobile/lib/presentation/widgets/asset_viewer/bottom_bar.widget.dart

@@ -71,16 +71,13 @@ class ViewerBottomBar extends ConsumerWidget {
                 ),
                 child: SafeArea(
                   top: false,
-                  child: Padding(
-                    padding: const EdgeInsets.only(top: 16),
-                    child: Column(
-                      mainAxisSize: MainAxisSize.min,
-                      children: [
-                        if (asset.isVideo) VideoControls(videoPlayerName: asset.heroTag),
-                        if (!isReadonlyModeEnabled)
-                          Row(mainAxisAlignment: MainAxisAlignment.spaceEvenly, children: actions),
-                      ],
-                    ),
+                  child: Column(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      if (asset.isVideo) VideoControls(videoPlayerName: asset.heroTag),
+                      if (!isReadonlyModeEnabled)
+                        Row(mainAxisAlignment: MainAxisAlignment.spaceEvenly, children: actions),
+                    ],
                   ),
                 ),
               ),

mobile/lib/theme/theme_data.dart

@@ -62,6 +62,7 @@ ThemeData getThemeData({required ColorScheme colorScheme, required Locale locale
     ),
     chipTheme: const ChipThemeData(side: BorderSide.none),
     sliderTheme: const SliderThemeData(
+      trackHeight: 12,
       // ignore: deprecated_member_use
       year2023: false,
     ),

mobile/lib/widgets/asset_viewer/video_controls.dart

@@ -66,9 +66,9 @@ class VideoControls extends HookConsumerWidget {
     final isLoaded = duration != Duration.zero;
 
     return Padding(
-      padding: const EdgeInsets.all(24),
+      padding: const EdgeInsets.only(left: 16, right: 16, bottom: 12),
       child: Column(
-        spacing: 16,
+        spacing: 4,
         children: [
           Row(
             children: [
@@ -77,8 +77,8 @@ class VideoControls extends HookConsumerWidget {
                 padding: const EdgeInsets.all(12),
                 constraints: const BoxConstraints(),
                 icon: isFinished
-                    ? const Icon(Icons.replay, color: Colors.white, size: 32, shadows: _controlShadows)
-                    : AnimatedPlayPause(color: Colors.white, size: 32, playing: isPlaying, shadows: _controlShadows),
+                    ? const Icon(Icons.replay, color: Colors.white, shadows: _controlShadows)
+                    : AnimatedPlayPause(color: Colors.white, playing: isPlaying, shadows: _controlShadows),
                 onPressed: () => _toggle(ref, isCasting),
               ),
               const Spacer(),
@@ -91,7 +91,7 @@ class VideoControls extends HookConsumerWidget {
                   shadows: _controlShadows,
                 ),
               ),
-              const SizedBox(width: 16),
+              const SizedBox(width: 12),
             ],
           ),
           Slider(