[Fix] Sync Status Updates

[stevensJourney]

Overview

This fixes the sync status indicator which did not emit any updates for uploading or downloading.

Sync status updates for uploading or downloading can be quite fast. The demo has been updated to debounce the flow. A nicer UI might be to trigger some animation based off uploading/downloading.

status.mp4

[simolus3]

These changes look good to me 👍

At least for the downloading state, we can write pretty accurate tests now. Something like this could go to SyncIntegrationTest.kt:

    @Test
    fun setsDownloadingState() = runTest {
        val syncStream = syncStream()
        database.connect(syncStream, 1000L)

        turbineScope(timeout = 10.0.seconds) {
            val turbine = database.currentStatus.asFlow().testIn(this)
            turbine.waitFor { it.connected && !it.downloading }

            syncLines.send(SyncLine.FullCheckpoint(Checkpoint(
                lastOpId = "1",
                checksums = listOf(BucketChecksum(
                    bucket = "bkt",
                    checksum = 0,
                ))
            )))
            turbine.waitFor { it.downloading }

            syncLines.send(SyncLine.CheckpointComplete(lastOpId = "1"))
            turbine.waitFor { !it.downloading }
            turbine.cancel()
        }

        database.close()
        syncLines.close()
    }