fix: show discrete GPU as default within cosmic context menu

PrefersNonDefaultGPU is specified as follows in the Specification:
  If true, the application prefers to be run on a more powerful discrete
  GPU if available, which we describe as “a GPU other than the default
  one” in this spec to avoid the need to define what a discrete GPU is
  and in which cases it might be considered more powerful than the
  default GPU. This key is only a hint and support might not be present
  depending on the implementation.
  https://specifications.freedesktop.org/desktop-entry/latest/recognized-keys.html

Checking for a Discrete GPU is a more accurate implementation
despite the misleading name.

plugins/src/desktop_entries/mod.rs

@@ -299,7 +299,7 @@ impl<W: AsyncWrite + Unpin> App<W> {
 
         if let Some(gpus) = self.gpus.as_ref() {
             let default_idx = if entry.prefers_non_default_gpu() {
-                gpus.iter().position(|gpu| !gpu.default).unwrap_or(0)
+                gpus.iter().position(|gpu| gpu.discrete).unwrap_or(0)
             } else {
                 gpus.iter().position(|gpu| gpu.default).unwrap_or(0)
             };