[TextInputLayout] Exposed the style of the ExposedDropDownMenu

[gabrielemariotti]

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Currently the ExposedDropDownMenu provided by DropdownMenuEndIconDelegate doesn't use the shapeAppearance defined in the app theme and the corner radius are defined by code.

With this change:

• the ExposedDropDownMenu uses the shapeAppearance defined in the app theme
• there is a new attribute exposedDropDownMenuStyle defined in the TextInputLayout style with allows to customize the shapeAppearance /shapeAppearanceOverlay (and some other properties) of the ExposedDropDownMenu.

This change can be tested with the current catalog (changing the shapeAppearance).