fix(windows): show split tooltip before move

[Nerixyz]

I believe #5189 is a Windows only bug. This PR fixes tooltips of splits appearing in the wrong position [after the first hover(?)] on Windows. The issue might also occur when a streamer goes offline and the thumbnail isn't shown, but I didn't test that.
While debugging, I noticed that even though we call adjustSize which, according to the documentation, adjusts the area its children occupy, the tooltip still has a larger size than expected. It's only adjusted when calling show() _{(if you want to reproduce this, try placing logpoints in QLayoutPrivate::doResize, QWidget::setGeometry, and QWidgetPrivate::setGeometry_sys)}.

For non-Windows platforms, nothing changes.
On Windows, the tooltip is now shown before it's moved. This is fine on Windows, as the new window doesn't become visible right after calling show() (only after processing some more events). Since a lot of the resizing/activating happens in show(), the window has the correct size afterward, and moveTo-ing it will place it at the desired position.
I don't know why we don't need to do this for the tooltips in ChannelView.

Fixes #5189. @8thony could you test the change? Make sure you place the window on some side of your screen.

I have a fix for the bug I mentioned in #5189 (comment) (it's one line), but I suppose it's better to do that separately.

[8thony]

Seems to work the same as on 2.4.6, thanks