Reorganize connection dialog

[KoBeWi]

Makes it more compact.

Before and after:

• Advanced button is now at the bottom, so that it doesn't cut method name
• Deferred and Oneshot are now next to each other

[fire-forge]

feels like they should be somewhere else entirely, as they make funny stairs right now

To avoid the funny stairs, the "Advanced" button could be under the "Receiver Method" LineEdit. It would be less compact, but the labels, LineEdits, and buttons would line up perfectly.

[KoBeWi]

Ok pushed this as a second commit, but something is still wrong lol

Also it's funny how whole dialog moves 1 pixel when toggling Advanced mode:

[seppoday]

Maybe move toggle to left side. That way it won't move to right side when you toggle it. It will stay in same place. Also it looks similar to Deffered/Oneshot checkboxes. More consistent?

[fire-forge]

The left and right side nodes still don't line up. It appears to be caused by the LineEdit nodes being 1px shorter than button nodes. Increasing the LineEdit StyleBox heights by 1px in the editor theme (editor_themes.cpp) should fix it. This would also affect other LineEdits throughout the editor, but hopefully it doesn't cause any problems.

[KoBeWi]

This is as much as I can align

Tree doesn't have any way to increase its size and I can't use custom minimum size, as it fits to window.

[akien-mga]

Thanks!