Drop the update check - Steam updates the starter

The daily GitHub check, the top-bar button, the stable/staging channel and
"check now" go, with their settings and texts.

StarterNG/Application/Abstractions/IReleaseFeed.cs

@@ -1,28 +0,0 @@
-using System.Threading;
-using System.Threading.Tasks;
-using StarterNG.Domain.Settings;
-
-namespace StarterNG.Application.Abstractions;
-
-/// <summary>
-/// A published build of the starter: its tag, the page it is downloaded from and
-/// the commit it was built from - the only way to tell rolling builds apart.
-/// </summary>
-public sealed record ReleaseInfo(string Tag, string PageUrl, string? Commit = null);
-
-/// <summary>
-/// What asking for the newest release came back with. No answer - offline, rate
-/// limited, timed out - is kept apart from an answer of "nothing released", so a
-/// failed check is not remembered as a done one.
-/// </summary>
-public sealed record ReleaseLookup(bool Answered, ReleaseInfo? Release)
-{
-    public static ReleaseLookup NoAnswer { get; } = new(false, null);
-
-    public static ReleaseLookup Found(ReleaseInfo? release) => new(true, release);
-}
-
-public interface IReleaseFeed
-{
-    Task<ReleaseLookup> LatestAsync(UpdateChannel channel, CancellationToken cancellationToken = default);
-}