New welcome screen

[engalali9]

[nathandyer]

@ali-sameh-galal Good day! Thanks for this PR!

I tried this out on my system to see how I felt about it in practice, but so far I don't think I'm a fan of this change. This is what I see when I launch it on my system:

The main issues I have with it are:

• The welcome screen appears in the center, while the main window is in another spot
• I can't move either the welcome screen or the main window until I acknowledge the welcome screen and click Get Started
• Overall, I feel like it's less cohesive

Is there a benefit to having the welcome screen broken out into a separate window like this? If so, I'm certainly open to being persuaded, but right now I'm not convinced this would be a beneficial change.