[Bug 45245] New: Add StartupWMClass also to bundled .desktop files such as wine-notepad.desktop

https://bugs.winehq.org/show_bug.cgi?id=45245

Bug ID: 45245
           Summary: Add StartupWMClass also to bundled .desktop files such
                    as wine-notepad.desktop
           Product: Wine
           Version: unspecified
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: programs
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Since the resolution of bug 32699, wine adds StartupWMClass=foo.exe to the
.desktop files it generates, matching the name/instance string of the WM_CLASS
it sets on wine windows. This has massively improved the integration of Wine
clients with desktop environments and made the users of KDE Plasma (and likely
Gnome Shell, which works the same way) much happier.

However, we've recently noticed that wine .desktop files installed in /usr and
presumably pre-generated/bundled haven't been updated in the same way. For
example, `wine-notepad.desktop` doesn't contain StartupWMClass=notepad.exe, so
the integration doesn't work there.

Fixing this up would allow the "Pin" and "Start New Instance" actions and even
listings of recently open files to work in the context menu of tasks like
Notepad in KDE Plasma, for example.