WaitBlocksTask should show progress in the UI

[rakanalh]

The scenario player currently only shows:

│2019-09-11 12:47:16.701089 [info     ] Starting task                  [scenario_player.tasks.base] task=<WaitBlocksTask: 401> 

However, i think it would be pretty nice to show the current block number, which gets updated after each block is created so that the task's progress can be seen.

[ulope]

Good idea, should maybe not log every block though (otherwise the various 401 block waits will create a log of log spam).
Maybe only log every blocks_to_wait / 10 blocks if blocks_to_wait > 15 or something like that?

[rakanalh]

Maybe we shouldn't log anything. The task is marked "in progress" in the list of tasks. Maybe we can place an addition to the label saying "(X / 401)"