Async BLAST Sync [2/N]: Introduce seqId

We introduce a seqId and use it to replace the
RELAYOUT_RES_BLAST_SYNC flag. The server code block that
produces RELAYOUT_RES_BLAST_SYNC is guarded by
mNextRelayoutUseSync, and sets it to false when executed.
This block is the only place that sets it to false. We replace
every place where it is set to true, with incrementing a seqId
stored on the integer. We change this block to not check
mNextRelayoutUseSync but instead check if the seqId has changed
since we reached the block. This is evidentally equivalent conditions
and in these cases we send the client the seqId. In the else block
where we wouldn't have sent RELAYOUT_RES_BLAST_SYNC we send -1.
On the client side, we replace the USE_BLAST_SYNC conditional
with a check if the SeqId we received has increased. It's clear
that this will never execute in cases where the seqId is -1. Likewise
its clear that if the seqId has increased, it will execute. Since the
seqId increases in all cases where the server would have returned
RELAYOUT_RES_BLAST_SYNC this change is a noop by itself.

Bug: 161810301
Bug: 175861051
Bug: 175861127
Bug: 200285149
Change-Id: Ib2e45cae7709519251e4bfcc2b8adc689c590a00