Refactor in one unique command with subcommand + add a new command to generate ressources from a configuration file

Sources/ResgenSwift/Fonts/FontsToolError.swift

@@ -0,0 +1,31 @@
+//
+//  FontsToolError.swift
+//  
+//
+//  Created by Thibaut Schmitt on 13/12/2021.
+//
+
+import Foundation
+
+enum FontsToolError: Error {
+    case fcScan(String, Int32, String?)
+    case inputFolderNotFound(String)
+    case fileNotExists(String)
+    case writeExtension(String, String)
+    
+    var localizedDescription: String {
+        switch self {
+        case .fcScan(let path, let code, let output):
+            return "error:[\(Fonts.toolName)] Error while getting fontName (fc-scan --format %{postscriptname} \(path). fc-scan exit with \(code) and output is: \(output ?? "no output")"
+            
+        case .inputFolderNotFound(let inputFolder):
+            return " error:[\(Fonts.toolName)] Input folder not found: \(inputFolder)"
+            
+        case .fileNotExists(let filename):
+            return " error:[\(Fonts.toolName)] File \(filename) does not exists"
+            
+        case .writeExtension(let filename, let info):
+            return "error:[\(Fonts.toolName)] An error occured while writing extension in \(filename): \(info)"
+        }
+    }
+}