wait for previous sync status poll to finish before polling again
wait for previous sync status poll to finish before polling again

previously, the status update async function was called every 1 second
no matter what, meaning that if the /consensus endpoint was ever
unresponsive, lots of HTTP calls could build up and on some platforms
this would cause the OS's file handle limit to be reached.

NebulousLabs/New-Sia-UI,NebulousLabs/New-Sia-UI,NebulousLabs/Sia-UI,NebulousLabs/Sia-UI,NebulousLabs/New-Sia-UI,NebulousLabs/Sia-UI