Use autofill specific dialog background

Autofill bottomsheet dialog would like to use the material 3
design. So we change the background color but the file is used
by other modules, we should not change it. So we create a seprate
background for autofill dialog background.

Bug: 233657077
Test: manual.
Change-Id: I9968c864ae9de78faab4dc8e6427c960c36584d6