blast: update hasDrawingBuffer to hasFrameUpdate

hasFrameUpdate is a more accurate name than hasDrawingBuffer.
Also keep track of when the current state has been modified
and only return true for BufferStateLayer::hasFrameUpdate
when the state has been modified and the buffer is not null.

Test: Transaction_test
Bug: 80477568

Change-Id: Icec6cf62490799988bd967914986bf92a07ce726