[NexusLauncher] Expose setLayoutHorizontal.

mLayoutHorizontal is exposed so that classes that extend BubbleTextView
can override this programmatically based on LayoutType.

mLayoutHorizontal prevents the title in horizontal cases affecting the
icon bounds measure, and shifting things such as the icon halo.

Bug: b/288471727
Test: See ag/24199217
Test: New tests in SearchResultIconTest
Test: No regression in SearchResultSmallIconRowTest
Change-Id: I424c1597d29ed26d7dea9e666ff2d274847e3217