refactor: Implement bottom navigation bar

This commit introduces a bottom navigation bar to the chat interface.

Key changes include:
- Added a `Scaffold` with a `BottomAppBar` in `ChannelNavigator`.
- The `BottomAppBar` contains `NavigationBarItem`s for "Home", "Friends", and "You" (Overview).
- The "Home" destination now displays the `Sidebar`.
- Removed the tablet-aware UI logic and the dismissible navigation drawer implementation.
- Simplified `ChannelNavigator` parameters, removing `useDrawer`, `disableBackHandler`, `onEnterVoiceUI`.
- Updated screen composables (`FriendsScreen`, `NoCurrentChannelScreen`, `ChannelScreen`, `OverviewScreen`) to remove the `useDrawer` parameter and its associated logic, as the drawer is no longer directly managed by these screens.
- Removed `drawerState` parameter from `ChannelSideDrawer` and related components, as drawer state is now managed differently.
- Removed logic related to closing the drawer on item clicks within `ChannelSideDrawer`.
- Added a new `ChatRouterDestination.Home`.
- Request for `POST_NOTIFICATIONS` permission is now correctly using `Manifest.permission.POST_NOTIFICATIONS`.

app/src/main/java/chat/revolt/activities/MainActivity.kt

@@ -629,7 +629,6 @@ fun AppEntrypoint(
                         ChatRouterScreen(
                             navController,
                             windowSizeClass,
-                            disableBackHandler = showVoiceUI,
                             onNullifiedUser = {
                                 onRetryConnection()
                                 navController.popBackStack(