Get PiP bounds from layout dimensions if applicable

Per CDD change proposal, will honor the layout dimensions such as
AndroidManifest_minWidth / AndroidManifest_minHeight specified by an
activity. Specs in detail: go/cdd-proposal-pip-size

Bug: 147360777
Test: atest PinnedStackTests PipBoundsHandlerTest
Change-Id: I9752aa272968eff15eb7dd2a46ae4591c1c5727f