Add ability to set PROVISIONED or ON_DEMAND stream modes (#7)
When using ON_DEMAND the base cost is that of roughly 4 provisioned shards which then has higher costs for ingress / egress as compared to PROVISIONED. It does alleviate the need to manually manage shards or configure a custom auto-scaling routine for this system so can be used to great effect in terms of system stability.
Big thanks @jordan-tr for the contribution!