The few other cases that used SimpleConfig.get_instance() now
either get passed a config instance, or they try to get a reference
to something else that has a reference to a config.
(see lnsweep, qt/qrcodewidget, qt/qrtextedit)
Previously commands did not run on the asyncio thread but now they do.
"restore" was polling like "while 1: time.sleep()", blocking the event loop.
Now "restore" does not sync the wallet; which is actually cleaner
as previously this wallet would never get unloaded from the daemon (syncing forever).
This is also symmetric with the "create" cmd which also does not try to sync with the network.
However now it became difficult to write a script that restores a wallet and wants to wait
until it gets synced. Workaround for now is to poll with "list_wallets" whether it's synced.
We could create a new command that blocks until the loaded wallet gets synced.
