Fix the issue of "copy" shortcut (ctrl+C) not copying the content

Fixed the following issue:
When user goes to bookmarks page and uses "Copy Link" button, it's copying the bookmarks page url instead of the post link.

Add support for x.com links.

The new version introduces a new feature to allow users to copy modify links on copy command directly instead of a custom shortcut. Users can enable/disable this feature from the add-on popup.

In version 2.0.0, users will have the ability to choose between vxtwitter and fxtwitter links. By default the extension uses vxtwitter links. You can enable the option Enable fxtwitter from the extension popup to use fxtwitter links instead of vxtwitter.