Screenshot doesn't work in older IOS devices

### Description

The Essentials screenshot feature is using api that doesn't exist in IOS12 or lower or if a user doesn't use Scenes.

After this issue is fixed we need to enable this test for other api versions on device tests #4833

https://github.com/dotnet/maui/pull/4833/files#diff-65433907ac65c89edf59c6e515ae2da6fb139f3d9d47ee4764531b0648c899bcR17

### Steps to Reproduce

Open the sample app
Go to screenshot screen on iOS 12 device

### Version with bug

Preview 13 (current)

### Last version that worked well

Unknown/Other

### Affected platforms

iOS

### Affected platform versions

iOS 12 and lower

### Did you find any workaround?

_No response_

### Relevant log output

_No response_

Start with the Essentials sample app and its screenshot screen, then inspect the referenced pull request #4833 and its device-test change. Reproduce the failure on an iOS 12-or-lower device and on a device without Scenes. Done means the screenshot feature works on those configurations and the test can be enabled for the other API versions.

Written by the indexing model from the issue text.