[material_ui] Fix bottom sheet dismissal near minimum extent when shouldCloseOnMinExtent - #12392

Fixes bottom sheet dismissal when a DraggableScrollableNotification extent
is within floating-point precision of minExtent, instead of requiring exact
equality.

Updates both the modal BottomSheet and standard Scaffold bottom sheet
handlers. Adds regression tests for both paths using extent: 0.20000000001
and minExtent: 0.2.

Also bumps material_ui to 0.0.4 and updates its CHANGELOG.

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