Force modal's content take all available width

[mikhailChelbaev]

Previously, if the content's width was smaller than the modal's width, it would align to the left. With this fix, the content now uses the full available width and centers itself.

Here's a sample code to test it:

struct App: View {
  @State var isModalPresented = false
  
  var body: some View {
    SUButton(model: .init {
      $0.title = "Show Modal"
    }) {
      isModalPresented = true
    }
    .bottomModal(
      isPresented: $isModalPresented,
      model: .init(),
      header: {
        Text("Header")
      },
      body: {
        Text("Body content goes here")
      },
      footer: {
        SUButton(model: .init {
          $0.title = "Close"
        }) {
          isModalPresented = false
        }
      }
    )
  }
}