chore: update snippets & event-handler docs

[dreamorosi]

Summary

Changes

Please provide a summary of what's being changed

This PR updates the following items after the last release:

• update CloudFormation template for AppSync Events + Lambda
• update one code snippet in the AppSync Events page, fix typo in key features, add clarification about REQUEST_RESPONSE
• add the new package as dev dependencies of the internal examples/snippets workspace following release
• update the Lambda layer ARNs for the new release (script to be fixed as part of Maintenance: update layer update script to bump GovCloud ARN #3772)
• mark @aws-lambda-powertools/event-handler as GA in next release
• update POWERTOOLS_DEV table formatting

Please add the issue number below, if no issue is present the PR might get blocked and not be reviewed

Issue number: closes #3863

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[leandrodamascena]

Hi @dreamorosi! I just left a comment that's worth checking out.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud