[com.google.android.material.bottomsheet] Expanded BottomSheetDialog shouldn't have top insets when it's in the bottom split screen

Nobody has claimed this yet.

**Description:**

Expanded BottomSheetDialog shouldn't have top insets when it's in the bottom split screen.

**Repro steps:**

1. Open app in portrait
1. Open Recents
1. Select "split screen"
1. Press the button to open the BottomSheetDialog
1. Double-tap on the handle between the screens
==> App moves to the bottom split screen. Extra top insets above the header.

Expected behavior: there wouldn't be top insets above the header.


This only occurs for expanded bottom sheets. This issue doesn't occur on Android 14. Note edge-to-edge was enforced on Android 15.

Sample app attached.

[BottomSheetDialogTest.zip](https://github.com/user-attachments/files/17237120/BottomSheetDialogTest.zip)

**Android API version:**

Android 15 (SDK 35)

**Material Library version:**

1.13.0-alpha06

**Device:**

Tested on Pixel Fold

Start with the attached BottomSheetTest.zip sample app and reproduce the expanded BottomSheetDialog issue on Android 15 (SDK 35) in the bottom split screen, comparing the Android 14 behavior. Trace the BottomSheetDialog inset handling; done means the expanded sheet has no extra top inset above its header in the reported configuration.

Written by the indexing model from the issue text.