Display download progress when using Azure Storage SDK

[dhadka]

Creates a timer to display download progress every second, including the # of bytes received and the average download speed. This is intended to provide better visibility into the download, especially for larger caches.

Here's an example restoring a 500 MB cache:

##[debug]Archive Path: /home/runner/work/_temp/7ad5a251-5ec2-455f-ad81-d9968ddcad82/cache.tzst
##[debug]Use Azure SDK: true
##[debug]Download concurrency: 8
##[debug]Request timeout (ms): 30000
##[debug]Downloading segment at offset 0 with length 524301052...
Received 171966464 of 524301052 (32.8%), 164.0 MBs/sec
Received 268435456 of 524301052 (51.2%), 127.9 MBs/sec
Received 486539264 of 524301052 (92.8%), 154.6 MBs/sec
Received 524301052 of 524301052 (100.0%), 143.6 MBs/sec
Cache Size: ~500 MB (524301052 B)
/bin/tar --use-compress-program zstd -d -xf /home/runner/work/_temp/7ad5a251-5ec2-455f-ad81-d9968ddcad82/cache.tzst -P -C /home/runner/work/cache-canary/cache-canary

[aiqiaoy]

toolkit-audit check failure is a known issue: https://github.slack.com/archives/D010RN1245D/p1594736728009600