dev/sg: submitting analytics needs a progress bar

Created by: burmudar

Spurred by @bobheadxi mentioning the slowness of sg update in https://github.com/sourcegraph/sourcegraph/issues/37852 I opted to submit my analytics. I had 896 events that could be submitted and submitted all of them with sg analytics submit.

It took quite a while +- 5 mins where there was no feedback. I think showing a progress bar with how many events have been submitted and how many are left would help here!