Add visibility parameters to control scope of generated extension

Sources/ResgenSwift/Strings/Stringium/Stringium.swift

@@ -72,7 +72,8 @@ struct Stringium: ParsableCommand {
                 inputFilename: options.inputFilenameWithoutExt,
                 extensionName: extensionName,
                 extensionFilePath: extensionFilePath,
-                extensionSuffix: options.extensionSuffix ?? ""
+                extensionSuffix: options.extensionSuffix ?? "",
+                visibility: options.extensionVisibility
             )
         }
 

Sources/ResgenSwift/Strings/Stringium/StringiumOptions.swift

@@ -7,6 +7,7 @@
 
 import ArgumentParser
 import Foundation
+import ToolCore
 
 // swiftlint:disable no_grouping_extension
 
@@ -23,7 +24,7 @@ struct StringiumOptions: ParsableArguments {
 
     @Option(
         name: .customLong("output-path"),
-        help: "Path where to strings file.",
+        help: "Path where to find the .xcStrings file or the lproj folders.",
         transform: { $0.replaceTiltWithHomeDirectoryPath() }
     )
     fileprivate var outputPathRaw: String
@@ -49,6 +50,13 @@ struct StringiumOptions: ParsableArguments {
     @Option(help: "Tell if it will generate xcStrings file or lproj file. True by default")
     var xcStrings: Bool = true
 
+    @Option(
+        name: .customLong("visibility"),
+        help: "Visibility of extension and properties. Possibles values: public, private, package, internal. Default is internal",
+        completion: .list(["public", "private", "package", "internal"])
+    )
+    var extensionVisibility: ExtensionVisibility = .internal
+
     @Option(
         help: "Path where to generate the extension.",
         transform: { $0.replaceTiltWithHomeDirectoryPath() }