Add edge highlight to "argon" slider repeat arrow (and improve all skins' reverse arrow animations)

[peppy]

Addresses concerns raised at #24984.

• Depends on Add repeat-edge-piece texture for argon sliders osu-resources#287.

I think this is something which has to be fixed as a priority, as it was shockingly broken. So, priority given.

---

This addresses concerns about visibility of repeat arrows on short sliders by adding a border element which animated outwards.

I've also fixed multiple inconsistencies when compared to stable, including disabling beat sync and having the animation start as soon as the hit object appears. This helps massively with visibility, as otherwise the animation may not start until much later. It also looks better as every slider is not longer synchronised to the same animation cycle.

osu.2023-10-02.at.10.08.59.mp4

osu.Game.Rulesets.Osu.Tests.2023-10-02.at.11.12.22.mp4

[bdach]

Kinda weird that there are event handlers being registered both in BDL and LoadComplete().

[peppy]

The animation doesn't play without it being here. We could try moving the other one here though?

[bdach]

If it works, sure. If it doesn't, I guess I'll live with it.

[peppy]

Honestly I'm not sure I'd feel safe changing it in this PR, so overlooking may be best 😅.

[bdach]

Made a comparison video (google drive because it doesn't embed for whatever reason): https://drive.google.com/file/d/1MziNMMSNVGQ1zRjigA-bqhZPAf-qBOrR/view?usp=sharing

I think the rotation animation on the v1 skins still looks a bit wonky, and is improved by applying

diff --git a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
index 34bcf95e1d..5164dc3240 100644
--- a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
+++ b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
@@ -39,7 +39,10 @@ private void load(ISkinSource skinSource)
 
             var skin = skinSource.FindProvider(s => s.GetTexture(lookupName) != null);
 
-            InternalChild = arrow = (skin?.GetAnimation(lookupName, true, true, maxSize: OsuHitObject.OBJECT_DIMENSIONS) ?? Empty());
+            InternalChild = arrow = (skin?.GetAnimation(lookupName, true, true, maxSize: OsuHitObject.OBJECT_DIMENSIONS) ?? Empty()).With(arr =>
+            {
+                arr.Anchor = arr.Origin = Anchor.Centre;
+            });
             textureIsDefaultSkin = skin is ISkinTransformer transformer && transformer.Skin is DefaultLegacySkin;
 
             drawableObject.ApplyCustomUpdateState += updateStateTransforms;

Before:

2023-10-02.22-36-20.mp4

After:

2023-10-02.22-36-57.mp4

[peppy]

Made a comparison video (google drive because it doesn't embed for whatever reason): drive.google.com/file/d/1MziNMMSNVGQ1zRjigA-bqhZPAf-qBOrR/view?usp=sharing

I think the rotation animation on the v1 skins still looks a bit wonky, and is improved by applying

diff --git a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
index 34bcf95e1d..5164dc3240 100644
--- a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
+++ b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyReverseArrow.cs
@@ -39,7 +39,10 @@ private void load(ISkinSource skinSource)
 
             var skin = skinSource.FindProvider(s => s.GetTexture(lookupName) != null);
 
-            InternalChild = arrow = (skin?.GetAnimation(lookupName, true, true, maxSize: OsuHitObject.OBJECT_DIMENSIONS) ?? Empty());
+            InternalChild = arrow = (skin?.GetAnimation(lookupName, true, true, maxSize: OsuHitObject.OBJECT_DIMENSIONS) ?? Empty()).With(arr =>
+            {
+                arr.Anchor = arr.Origin = Anchor.Centre;
+            });
             textureIsDefaultSkin = skin is ISkinTransformer transformer && transformer.Skin is DefaultLegacySkin;
 
             drawableObject.ApplyCustomUpdateState += updateStateTransforms;

Before:

2023-10-02.22-36-20.mp4

After:

2023-10-02.22-36-57.mp4

Nice find. I was wondering why this looked so wrong but it's such a rare occurrence in skinning that I didn't really care enough to fix immediately.

[bdach]

Updated comparison: https://drive.google.com/file/d/12xAX1XJhYuoQ0xXO_omGouios1o7XEhj/view

Looks about as good as can get. Just need the resources change to go through and we can probably wrap this up.