feat: Add a rds-instance-stop chaos fault

[jongwooo]

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What this PR does / why we need it:

I have implemented the rds-instance-stop chaos fault in this PR based on the proposal.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Please see also https://github.com/litmuschaos/litmus-go/pull/710

cc. @namkyu1999