Flyout rework

[bdlukaa]

• Removed Flyout.contentWidth and added FlyoutContent.constraints. Now the content will be automatically sized and layed out according to the placement
• Added Flyout.placement which takes a FlyoutPlacement
• Added Flyout.openMode which takes a FlyoutOpenMode
• Flyout.controller is no longer required. If not provided, a local controller is created to handle the Flyout.openMode settings
• Breaking FlyoutController.open is now a function
• Adedd FlyoutController.isOpen, FlyoutController.isClosed, FlyoutController.close(), FlyoutController.open() and FlyoutController.toggle()

Pre-launch Checklist

• I have updated CHANGELOG.md with my changes
• I have run "optimize/organize imports" on all changed files
• I have added/updated relevant documentation