Save the position / size of ExternSimDialog on exit.

[iwbnwif]

This is a simple change to store the last used position and size of the "Simulate with external simulator" dialog (class ExternSimDialog) when the user presses the "Exit" button.

This change should close #1012 and work on all platforms but I have only tested it on Linux / Qt6.

[iwbnwif]

@tomhajjar, @ainst please let me know if this addresses the issue.

[ra3xdh]

I have tested this PR and noticed the following problem. When using Wayland+Qt6.7.2 the window size is restored, but the window position is not restored. The dialog always positioned in the display center. I am not sure if this is patch issue or Wayland issue. Wayland may not allow to set the initial position of the dialog windows. I didn't test Windows and X11.

[iwbnwif]

Unfortunately, I cannot get Wayland to run well on my computer.

If you are using Gnome and have Gnome Tweaks installed, please can I ask you to check the setting Windows->Centre New Windows. The behavior of this setting appears to be different between X11 and Wayland.

[ra3xdh]

I am using KDE. The KDE has a similar setting but it seems it has no effect. Let's consider this as some KDE+Wayland bug or feature. I am merging this.