featureRequest: Re-factor flow trigger logic

[leelalagudu]

• The solution currently uses DynamoDB stream events as the source for triggering the flow logic for both account assignment and permission set flows.
• Using this mechanism limits ability to implement observability logic as the stream trigger creates a disconnect between any interface trigger and solution processing flow.
• The recommendation is to replace the trigger point to be an SNS topic so that the trace ID would be persisted between the interface trigger and solution processing flow.