Standardize osu!catch coordinate system

There were two coordinate systems used:
- 0..512 (used in osu!stable)
- 0..1 (relative coordinate)

This commit replaces the usage of
the relative coordinate system to
the coordinate system of 0..512.

osu.Game.Rulesets.Catch/Objects/CatchHitObject.cs

@@ -5,6 +5,7 @@ using osu.Framework.Bindables;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Catch.Beatmaps;
+using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Scoring;
@@ -17,6 +18,9 @@ namespace osu.Game.Rulesets.Catch.Objects
 
         private float x;
 
+        /// <summary>
+        /// The horizontal position of the fruit between 0 and <see cref="CatchPlayfield.WIDTH"/>.
+        /// </summary>
         public float X
         {
             get => x + XOffset;