Fix script button press in connections dialog

[Giganzo]

Fixes: https://github.com/godotengine/godot/issues/99854

Script button will now connect the signal to the script when clicked.

When script button is pressed in the Scene tree dock it opens the script so I thought it would be nice if it opened/connected the script here too.

Screencast_20241129_230919.webm

[KoBeWi]

That's not really a bug. Also you can already connect by double-clicking the node, so doing it via the script button is redundant and unexpected. Maybe it should just open the script. Or, if it's possible, it should be non-clickable.

[Giganzo]

The best thing would be that the button was just an icon. But that requires a new column and was not able to get same behavior with that.

But I changed some things around. Single click on the script button just selects the row now. Double click on the script button connects the signal, so it should feel like it's just an "icon" and you clicked on the row.