Improve ergonomics about pagesheet HOT 1 CLOSED

Result of the investigation was to use enums & associated values:

struct SheetContentView: View {
  var body: some View {
    Text("Hello World")
        .sheetPreference(.grabberVisible(true))
  }
}

This satisfies the following:

• Easy to remember, understand without context, and provides useful code completion.
• Can be extended to provide new and tangential configuration options

The reason enums are used instead of key paths is that there is no equivalent struct to EnvironmentValues for preferences. It wouldn't really make sense to have one either, since preferences aren't consolidated that way. Enum provides most of the same functionality and shape as the KeyPath api.

from pagesheet.