Add Split button to Studio Controls

Problem:

User struggles to differentiate between project launch and component live preview on the current Design Studio UI.

Solution:

We need to change this so that there is only one CTA for the task. Other IDEs do this usually by combining different launch options to single button and open a list of actions when long keypress or button + shift is pressed.

QML Split Button does not exist yet in Quick Controls, so we need to implement this into Studio Controls so Design Studio can utilize this.

This needs UI design, can be done by hpaulaha or brook_cronin_qt.