Menu ShortcutKey improvements

- GitUI/Hotkey/KeysExtensions.ToFormattedString is now able to produce culture specific strings instead of English only (except for "None")
- FormBrowse: add "Go to current revision" to Commands menu
- For several menu items of the FormBrowse main menu: show the ShortcutKey as set in GitExt Settings: Commit, Go to current revision, Git bash