Add UI Mode Warning Dialog and Handle Device Mode Changes

[Himanth-reddy]

This pull request adds a confirmation dialog when changing the UI mode (e.g., TV, Tablet, Phone, Auto) in the settings screen. Instead of switching the mode immediately, users are now prompted to confirm their choice, improving the user experience and preventing accidental changes. The implementation introduces new state variables, a dialog composable, and updates the relevant event handlers.

UI Mode Change Confirmation:

• Added UiModeWarningDialog composable to display a confirmation dialog when the user attempts to change the UI mode, with keyboard and touch navigation support.
• Introduced new state variables showUiModeWarningDialog and nextUiMode to manage dialog visibility and the target UI mode.
• Refactored UI mode change triggers (e.g., onDeviceModeClick, settings option 11) to open the confirmation dialog instead of immediately switching the mode. [1] [2] [3]
• Added logic to compute the next UI mode and show the dialog when a change is initiated.
• Rendered the confirmation dialog in the settings screen when showUiModeWarningDialog is true, and applied the mode change only upon confirmation. [1] [2]