Add a modal Dialog component

[afarber]

Add a modal Dialog component to PixiUI for asking questions and presenting simple choices:

• Add support for any number of buttons, including none
• Emit onSelect signal with button index and text when user makes a selection
• Accept Graphics, Sprites, Textures, or texture names via GetViewSettings
• Supports closeOnBackdropClick to dismiss on a scrim tap
• Also add JSdoc comments to all methods in the stories/utils/*.ts files

[afarber]

Hi @CyberDex please take a look at my PR.

I am still working on it, but do you have any suggestions already?

[afarber]

Hi @Zyie @GoodBoyDigital @CyberDex please review my PR

[afarber]

Hi @CyberDex I have improved the PR:

• Dialog now uses animations option like FancyButton. When animations is not passed, the dialog opens/closes immediately without animation
• Custom FancyButtons can be passed to Dialog constructor via the button property

Below are screenshots demoing this - the Simple Alert story has no animations and the Confirm Dialog story uses custom FancyButtons with hover/press animations:

I don't see any color issues in the Storybook on my end. Could you please confirm if the colors still look weird to you?