Add license and settings overrides to LibationCli

- Add `LIBATION_FILES_DIR` environment variable to specify LibationFiles directory instead of appsettings.json
- OptionsBase supports overriding setting
  - Added `EphemeralSettings` which are loaded from Settings.json once and can be modified with the `--override` command parameter
- Added `get-setting` command
  - Prints (editable) settings and their values. Prints specified settings, or all settings if none specified
  - `--listEnumValues` option will list all names for a speficied enum-type settings. If no setting names are specified, prints all enum values for all enum settings.
  - Prints in a text-based table or bare with `-b` switch
- Added `get-license` command which requests a content license and prints it as a json to stdout
- Improved `liberate` command
  - Added `-force` option to force liberation without validation.
  - Added support to download with a license file supplied to stdin
  - Improve startup performance when downloading explicit ASIN(s)
  - Fix long-standing bug where cover art was not being downloading

Source/LibationFileManager/Configuration.PersistentSettings.cs

@@ -7,6 +7,7 @@ using System.Runtime.CompilerServices;
 using FileManager;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Linq;
 
 #nullable enable
 namespace LibationFileManager
@@ -18,12 +19,15 @@ namespace LibationFileManager
 		// default setting and directory creation occur in class responsible for files.
 		// config class is only responsible for path. not responsible for setting defaults, dir validation, or dir creation
 		// exceptions: appsettings.json, LibationFiles dir, Settings.json
-		private IPersistentDictionary? persistentDictionary;
-		private IPersistentDictionary Settings => persistentDictionary
+		private IJsonBackedDictionary? JsonBackedDictionary { get; set; }
+		private IJsonBackedDictionary Settings => JsonBackedDictionary
 			?? throw new InvalidOperationException($"{nameof(LoadPersistentSettings)} must first be called prior to accessing {nameof(Settings)}");
 
 		internal void LoadPersistentSettings(string settingsFile)
-			=> persistentDictionary = new PersistentDictionary(settingsFile);
+			=> JsonBackedDictionary = new PersistentDictionary(settingsFile);
+
+		internal void LoadEphemeralSettings(JObject dataStore)
+			=> JsonBackedDictionary = new EphemeralDictionary(dataStore);
 
 		private LibationFiles? _libationFiles;
 		[Description("Location for storage of program-created files")]