Move handling of replay seek operations out of progress bar

This is in order to avoid using the now obsoleted property
`SliderBar.AllowKeyboardInputWhenNotHovered`
(see https://github.com/ppy/osu-framework/pull/4579).

osu.Game/Input/Bindings/GlobalActionContainer.cs

@@ -87,6 +87,8 @@ namespace osu.Game.Input.Bindings
             new KeyBinding(new[] { InputKey.Shift, InputKey.Tab }, GlobalAction.ToggleInGameInterface),
             new KeyBinding(InputKey.MouseMiddle, GlobalAction.PauseGameplay),
             new KeyBinding(InputKey.Space, GlobalAction.TogglePauseReplay),
+            new KeyBinding(InputKey.Left, GlobalAction.SeekReplayBackward),
+            new KeyBinding(InputKey.Right, GlobalAction.SeekReplayForward),
             new KeyBinding(InputKey.Control, GlobalAction.HoldForHUD),
         };
 
@@ -272,5 +274,11 @@ namespace osu.Game.Input.Bindings
 
         [Description("Next volume meter")]
         NextVolumeMeter,
+
+        [Description("Seek replay forward")]
+        SeekReplayForward,
+
+        [Description("Seek replay backward")]
+        SeekReplayBackward,
     }
 }

osu.Game/Screens/Play/ReplayPlayer.cs

@@ -3,11 +3,15 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 using osu.Framework.Input.Bindings;
+using osu.Framework.Threading;
 using osu.Game.Beatmaps;
+using osu.Game.Extensions;
 using osu.Game.Input.Bindings;
 using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Scoring;
 using osu.Game.Screens.Ranking;
 
@@ -43,10 +47,24 @@ namespace osu.Game.Screens.Play
 
         protected override ResultsScreen CreateResults(ScoreInfo score) => new SoloResultsScreen(score, false);
 
+        private ScheduledDelegate keyboardSeekDelegate;
+
         public bool OnPressed(GlobalAction action)
         {
+            const double keyboard_seek_amount = 5000;
+
             switch (action)
             {
+                case GlobalAction.SeekReplayBackward:
+                    keyboardSeekDelegate?.Cancel();
+                    keyboardSeekDelegate = this.BeginKeyRepeat(Scheduler, () => keyboardSeek(-1));
+                    return true;
+
+                case GlobalAction.SeekReplayForward:
+                    keyboardSeekDelegate?.Cancel();
+                    keyboardSeekDelegate = this.BeginKeyRepeat(Scheduler, () => keyboardSeek(1));
+                    return true;
+
                 case GlobalAction.TogglePauseReplay:
                     if (GameplayClockContainer.IsPaused.Value)
                         GameplayClockContainer.Start();
@@ -56,10 +74,24 @@ namespace osu.Game.Screens.Play
             }
 
             return false;
+
+            void keyboardSeek(int direction)
+            {
+                double target = Math.Clamp(GameplayClockContainer.CurrentTime + direction * keyboard_seek_amount, 0, GameplayBeatmap.HitObjects.Last().GetEndTime());
+
+                Seek(target);
+            }
         }
 
         public void OnReleased(GlobalAction action)
         {
+            switch (action)
+            {
+                case GlobalAction.SeekReplayBackward:
+                case GlobalAction.SeekReplayForward:
+                    keyboardSeekDelegate?.Cancel();
+                    break;
+            }
         }
     }
 }

osu.Game/Screens/Play/SongProgressBar.cs

@@ -57,8 +57,6 @@ namespace osu.Game.Screens.Play
             set => CurrentNumber.Value = value;
         }
 
-        protected override bool AllowKeyboardInputWhenNotHovered => true;
-
         public SongProgressBar(float barHeight, float handleBarHeight, Vector2 handleSize)
         {
             CurrentNumber.MinValue = 0;