Add abstract Section class

Similar to `Section` in the timing screen, but does not make use of checkboxes, nor specific to control points.

So there's a lot of things that differ, hence new class instead of factoring that out.

osu.Game/Screens/Edit/Verify/Section.cs

@@ -0,0 +1,67 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Graphics.Sprites;
+using osu.Game.Overlays;
+using osuTK;
+
+namespace osu.Game.Screens.Edit.Verify
+{
+    public abstract class Section : CompositeDrawable
+    {
+        private const int header_height = 50;
+
+        protected readonly IssueList IssueList;
+
+        protected FillFlowContainer Flow;
+        protected abstract string Header { get; }
+
+        protected Section(IssueList issueList)
+        {
+            IssueList = issueList;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OverlayColourProvider colours)
+        {
+            RelativeSizeAxes = Axes.X;
+            AutoSizeAxes = Axes.Y;
+            Masking = true;
+
+            InternalChildren = new Drawable[]
+            {
+                new Container
+                {
+                    RelativeSizeAxes = Axes.X,
+                    Height = header_height,
+                    Padding = new MarginPadding { Horizontal = 20 },
+                    Child = new OsuSpriteText
+                    {
+                        Anchor = Anchor.CentreLeft,
+                        Origin = Anchor.CentreLeft,
+                        Text = Header,
+                        Font = new FontUsage(size: 25, weight: "bold")
+                    }
+                },
+                new Container
+                {
+                    Y = header_height,
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
+                    Child = Flow = new FillFlowContainer
+                    {
+                        Padding = new MarginPadding { Horizontal = 20 },
+                        Spacing = new Vector2(10),
+                        RelativeSizeAxes = Axes.X,
+                        AutoSizeAxes = Axes.Y,
+                        Direction = FillDirection.Vertical,
+                    }
+                }
+            };
+        }
+    }
+}