Linux: Use NSIS installer (#991)

* feat: Implement SKIP_SHORTCUT for installer

* feat: Update Linux install script to use NSIS-based installer instead

* feat: Wine detection for installer shortcut suppression

* fix: Revert WINEPREFIX back to XDG Home

Oops.

* fix(linux): Forgot to use the variable here

* fix(linux): Don't error if INSTALL_LOCATION exists but is empty

* fix(linux): "Program Files" has a space

Dotnet/Program.cs

@@ -178,6 +178,7 @@ namespace VRCX
             Application.SetCompatibleTextRenderingDefault(false);
 
             logger.Info("{0} Starting...", Version);
+            logger.Debug("Wine support detection: {0}", Wine.GetIfWine());
             
             ProcessMonitor.Instance.Init();
             SQLiteLegacy.Instance.Init();