Make shouldBeSeamless an enum

We change theboolean shouldBeSemaless to an enum with
three values. This introduces a third value "Default" which
indicates that the layer doesn't have a preference for
seamlessness. This is the default value for Surfaces which
haven't called setFrameRate, or have called setFrameRate(0).

Bug: 161776961
Test: presubmit
Change-Id: I157e332e82e95badc928d6a8135e657cd6984db4