Desktop screenshots: Allow default selections in pre-capture UI

The pre-capture UI will set the capture type and capture region by
default based on the provided large-screen UI parameters. If no defaults
are provided, the state will be configured for fullscreen screenshots.
This effectively allows keyboard shortcuts to open the pre-capture UI
with specific initial options.

Bug: 420714826
Test: atest PreCaptureViewModelTest
Test: atest ScreenCaptureKeyboardShortcutInteractorTest
Flag: com.android.systemui.large_screen_screencapture
Change-Id: Id552bbf1022c555930141c51aba4e75ff97d686d