Add Keyboard Shortcuts for Deasciify Features in Firefox

[umitaltintas]

Feature: Add keyboard shortcuts for Deasciify features in Firefox

This pull request adds keyboard shortcuts for two features in the Firefox extension:

1. Deasciify Selected Text
   • Shortcut: Alt+Shift+D (Command+Alt+D on Mac)
2. Toggle Auto-Deasciify
   • Shortcut: Alt+Shift+A (Command+Alt+A on Mac)

These shortcuts allow users to quickly and easily access the extension's core functionalities without having to interact with the context menu or toolbar button.

Changes made:

1. Added listeners for the new shortcuts in background.js:

browser.commands.onCommand.addListener(function (command) {
  if (command === "DEASCIIFY_SELECTED_TOGGLE") {
  ConvertTurkishChars();
  }
 if (command === "AUTO_DEASCIIFY_TOGGLE") {
   browser.tabs.executeScript({ file: "execute.js" }, function () {
     browser.tabs.executeScript({ code: "toggleAutoDeasciify();" });
   });
 }
});

2. Added shortcut definitions in manifest.js:

"commands": {
  "DEASCIIFY_SELECTED_TOGGLE": {
    "suggested_key": {
      "default": "Alt+Shift+D",
      "mac": "Command+Alt+D"
    },
  "description": "Deasciify the selected text"
  },
  "AUTO_DEASCIIFY_TOGGLE": {
    "suggested_key": {
      "default": "Alt+Shift+A",
      "mac": "Command+Alt+A"
    },
  "description": "Toggle auto-deasciify"
  }
}

Please review the changes and let me know if you have any feedback or if any further changes are required.

Thank you!