Add progress bar for state sync

[r0wdy1]

See:

• https://github.com/zkBob/zkbob-client-js/issues/128

We need to show some progress while loading state. In order to do that pass a callback function to updateTotalBalance that will change a corresponding context variable used to render the progress bar

• There should be a simple percentage progress bar from 0% to 100%
• If we'd show 99% too long (more than 10 seconds) we need to show an additional message, e.g. "Almost done", "Just a couple more seconds"

[maikReal]

UPD: The lib part is ready. More details in the following PR: https://github.com/zkBob/zkbob-client-js/pull/160#issue-1840239802

@maxaleks

[vadimnikonov1]

QA review - OK