[AWSINST-3517] feat(go-forwarder): add EventBridge

[ndakkoune]

What does this PR do?

Adds EventBridge as supported event (both S3 and Cloudwatch) + refactor parsing logic to extract the payloads properly.

Motivation

Testing Guidelines

Additional Notes

• We only have one EventBridge handler which is triggered on EventBridge events not coming from S3, otherwise we format it as an S3 one and throw it to the s3 handler

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)
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