Fix window insets on ChatScreen with safeContentPadding()

[cartland]

The issue is more visible with 3 button navigation. The InputBar is obscured by the navigation bar.
Modifier.safeContentPadding() ensures that the ChatScreen is not obscured.

[cartland]

Before:

After:

[calren]

adding sysui expert @ashnohe

[ashnohe]

Thanks! Somehow this got removed from the main branch while we were working on the I/O codelabs.

This is the correct fix in ChatScreen around line 220:

InputBar(
    ...
    contentPadding = innerPadding.copy(layoutDirection, top = 0.dp), //Add this line.
    // contentPadding = innerPadding, // Remove this line.
    ...
 )

[cartland]

@ashnohe thanks! I updated with your suggestion.