Update query-cloudwatch to be able to query multiple dates (LG-11257)

[zachmargolis]

🎫 Ticket

LG-11257

🛠 Summary of changes

Adds a new --date option to query-cloudwatch that allows using the the time_slices option of our CloudwatchClient to query separate, disjoint dates with the same query, willl help with more efficient use of time in Cloudwatch and lower billing costs.

example:

> aws-vault exec prod-power -- \
  ./bin/query-cloudwatch \
  --date 2023-09-01,2023-08-01 \ # << NEW OPTION
  --env prod --app idp --log events.log \
  --query "fields @timestamp | stats count(*) by bin(1d)" \
  --no-progress
2023-09-01 00:00:00.000,20914416
2023-08-01 00:00:00.000,25423701