feat: New --app-data option for specifying app data directory

The target for this is mainly docker, where I want more control over
where and how the app data directory is structured and located.

src/Recyclarr.Tests/Command/Initialization/Init/InitializeAppDataPathTest.cs

@@ -0,0 +1,37 @@
+using AutoFixture.NUnit3;
+using NSubstitute;
+using NUnit.Framework;
+using Recyclarr.Command;
+using Recyclarr.Command.Initialization.Init;
+using TestLibrary.AutoFixture;
+using TrashLib;
+
+namespace Recyclarr.Tests.Command.Initialization.Init;
+
+[TestFixture]
+[Parallelizable(ParallelScope.All)]
+public class InitializeAppDataPathTest
+{
+    [Test, AutoMockData]
+    public void Do_not_override_path_if_null(
+        [Frozen] IAppPaths paths,
+        SonarrCommand cmd,
+        InitializeAppDataPath sut)
+    {
+        sut.Initialize(cmd);
+
+        paths.DidNotReceiveWithAnyArgs().SetAppDataPath(default!);
+    }
+
+    [Test, AutoMockData]
+    public void Override_path_if_not_null(
+        [Frozen] IAppPaths paths,
+        SonarrCommand cmd,
+        InitializeAppDataPath sut)
+    {
+        cmd.AppDataDirectory = "path";
+        sut.Initialize(cmd);
+
+        paths.Received().SetAppDataPath("path");
+    }
+}

src/Recyclarr/Command/Initialization/Init/InitializeAppDataPath.cs

@@ -0,0 +1,27 @@
+using System.IO.Abstractions;
+using TrashLib;
+
+namespace Recyclarr.Command.Initialization.Init;
+
+public class InitializeAppDataPath : IServiceInitializer
+{
+    private readonly IFileSystem _fs;
+    private readonly IAppPaths _paths;
+
+    public InitializeAppDataPath(IFileSystem fs, IAppPaths paths)
+    {
+        _fs = fs;
+        _paths = paths;
+    }
+
+    public void Initialize(ServiceCommand cmd)
+    {
+        if (string.IsNullOrEmpty(cmd.AppDataDirectory))
+        {
+            return;
+        }
+
+        _fs.Directory.CreateDirectory(cmd.AppDataDirectory);
+        _paths.SetAppDataPath(cmd.AppDataDirectory);
+    }
+}

src/Recyclarr/Command/Initialization/InitializationAutofacModule.cs

@@ -14,6 +14,7 @@ public class InitializationAutofacModule : Module
 
         // Initialization Services
         builder.RegisterTypes(
+                typeof(InitializeAppDataPath),
                 typeof(ServiceInitializer),
                 typeof(ServicePreInitializer))
             .As<IServiceInitializer>()

src/Recyclarr/Command/ServiceCommand.cs

@@ -23,7 +23,12 @@ public abstract class ServiceCommand : ICommand, IServiceCommand
         "If not specified, the script will look for `recyclarr.yml` in the same directory as the executable.")]
     public ICollection<string> Config { get; [UsedImplicitly] set; } = new List<string>();
 
-    public abstract string CacheStoragePath { get; protected init; }
+    [CommandOption("app-data", Description =
+        "Explicitly specify the location of the recyclarr application data directory. " +
+        "Mainly for usage in Docker; not recommended for normal use.")]
+    public string? AppDataDirectory { get; [UsedImplicitly] set; }
+
+    public abstract string CacheStoragePath { get; [UsedImplicitly] protected init; }
     public abstract string Name { get; }
 
     protected ServiceCommand(IServiceInitializationAndCleanup init)

src/TrashLib/Repo/RepoUpdater.cs

@@ -9,6 +9,7 @@ namespace TrashLib.Repo;
 public class RepoUpdater : IRepoUpdater
 {
     private readonly ILogger _log;
+    private readonly IAppPaths _paths;
     private readonly IGitRepositoryFactory _repositoryFactory;
     private readonly IFileUtilities _fileUtils;
     private readonly ISettingsProvider _settingsProvider;
@@ -21,13 +22,13 @@ public class RepoUpdater : IRepoUpdater
         ISettingsProvider settingsProvider)
     {
         _log = log;
+        _paths = paths;
         _repositoryFactory = repositoryFactory;
         _fileUtils = fileUtils;
         _settingsProvider = settingsProvider;
-        RepoPath = paths.RepoDirectory;
     }
 
-    public string RepoPath { get; }
+    public string RepoPath => _paths.RepoDirectory;
 
     public void UpdateRepo()
     {