Configurable album overlay background and default starting point for album overlay proposal

[MichaelNeas]

I was using this picker on a swiftui project and was asked to add albums to the picker I noticed issue #268

This PR adds:

• configurable background color to albumviewcontroller based on the theme
• checks for safe area insets if there is no navigation controller

In the DropdownPresentationController in swiftUI you can get:

type(of: presentingViewController)
> SwiftUI.SheetHostingController

And I'm not sure if we can get the underlying navigation bar height. However, instead of defaulting to .zero respecting safe area insets might be a nicer solution.