Move default repo addition to migration

Jellyfin.Server/Migrations/Routines/AddDefaultPluginRepository.cs

@@ -0,0 +1,44 @@
+using System;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Model.Updates;
+
+namespace Jellyfin.Server.Migrations.Routines
+{
+    /// <summary>
+    /// Migration to initialize system configuration with the default plugin repository.
+    /// </summary>
+    public class AddDefaultPluginRepository : IMigrationRoutine
+    {
+        private readonly IServerConfigurationManager _serverConfigurationManager;
+
+        private readonly RepositoryInfo _defaultRepositoryInfo = new RepositoryInfo
+        {
+            Name = "Jellyfin Stable",
+            Url = "https://repo.jellyfin.org/releases/plugin/manifest-stable.json",
+            Id = Guid.Parse("3721cd80-b10f-4b26-aecd-74c0f0defe97"),
+            Enabled = true
+        };
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AddDefaultPluginRepository"/> class.
+        /// </summary>
+        /// <param name="serverConfigurationManager">Instance of the <see cref="IServerConfigurationManager"/> interface.</param>
+        public AddDefaultPluginRepository(IServerConfigurationManager serverConfigurationManager)
+        {
+            _serverConfigurationManager = serverConfigurationManager;
+        }
+
+        /// <inheritdoc/>
+        public Guid Id => Guid.Parse("EB58EBEE-9514-4B9B-8225-12E1A40020DF");
+
+        /// <inheritdoc/>
+        public string Name => "CreateDefaultPluginRepository";
+
+        /// <inheritdoc/>
+        public void Perform()
+        {
+            _serverConfigurationManager.Configuration.PluginRepositories.Add(_defaultRepositoryInfo);
+            _serverConfigurationManager.SaveConfiguration();
+        }
+    }
+}