"Create a desktop shortcut" check box in installers

Change name of the "Installation Folder" page in the installer to "General Settings".
Change the label above the installation file path to "Unipro UGENE Installation Folder". If possible, move the label closer to the edit box.

On this page add "Create a desktop shortcut" check box.

If checked add an icon to the current user's Desktop that link to "ugeneui" in the UGENE installation folder. This should be:

• On Windows - a shortcut
• On macOS - an alias
• On Linux - "Unipro UGENE.desktop" file with the correct command, etc. (note that some Desktop file is available in the installation folder)

Make sure the feature works in case UGENE has been installed:

• into a folder with a space character in a path
• into a folder with non-ASCII characters in a path