Slim recents: make longpress options size better when small

When using Widget.Material.Light.Button.Borderless.Small,
the specified minHeight can make the buttons bigger than the
card, which leads to a growing card on longpress (that gets
smaller after exiting the options menu again).

To make it look better, add our own style instead.
When adding to much padding (tried 4dp), the same issues can
occur as described above, but 2dp seems to work fine.

Additionally, by adding our own style, we make it themable :)

Change-Id: I7e2c27f1164ca4c6e8863818ae5b2f7f59d36d08