feat: add sns->sqs->lambda support

[michael-zhao459]

What does this PR do?

This PR adds DSM support for sns -> sqs -> lamda, Changing the get_dsm_context() so that context can be properly extracted from the sqs -> lambda step. A checkpoint does not need to be set between queues.

Motivation

Many customers have SNS->SQS architecture, if only support SNS or only support SQS they will think the product is still broken

Testing Guidelines

Added unit tests

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)