Add new tables for listing and checking reserved instances and associated costs

[cbruno10]

Is your feature request related to a problem? Please describe.
Would love to see the ability to list reserved instances for EC2, RDS, Redshift, Elasticache, and Elasticsearch as part of the cost optimization pillar.

Opened from #47 (comment)

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[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[github-actions]

This issue was closed because it has been stalled for 90 days with no activity.