Replace Menu with ModalBottomSheet and add UiEvents, UiState

[dead8309]

Previously, the UI event handling in the CustomScreenViewModel relied on a different approach. This pr refactors the implementation to utilize channels for improved readability and conciseness.

Changes Made:

• Replace DrowDownMenu with a new ModalBottomSheet component.
• Add UiState Data class for storing all fields value along with some dialogs visibility values.
• Add UiEvent interface for passing events from UI to ViewModel.
• Introduced a new channel, uiEventChannel, to queue UI events.
• Modified the onEvent function to send events to the uiEventChannel.
• Added a coroutine in the init block to consume events from the uiEventChannel and process them sequentially.
• Updated the processEvent function to handle events and update the UI state accordingly.