<Swing Dev> Fix the hard coded mnemonic keys for JFileChooser in metal and motif LaF

[Pavel Porvatov]

Hi Charles,
> Hi Pavel,
>
> This is patch for sunbug 7024118. Would you please review it :-)
>
>
Your fix looks really good! I have a couple comments:

1. You are still using TAB characters. Stop it, please...
2. Would you like to fix WindowsLookAndFeel as well?

Regards, Pavel