Support osls v4 and remove dependency to AWS V2 SDK from serverless framework

[holzerch]

Expected Behavior

• Support osls V4 framework: https://github.com/oss-serverless/osls
• Remove dependency to outdated V2 AWS SDK e.g. here:

  serverless-plugin-datadog/src/forwarder.ts

  Line 118 in e7ce4fe

  await aws.request("Lambda", "getFunction", { FunctionName: functionArn });

  
  See migration guide: https://github.com/oss-serverless/osls/blob/4.x/docs/guides/upgrading-to-v4.md#aws-sdk-v2-removed-plugin-authors

Actual Behavior

• The plugin fails with osls v4

Steps to Reproduce the Problem

1. Run the plugin with osls v4

Specifications

• Serverless Framework version: osls v4
• Datadog Serverless Plugin version: 5.131.0
• Lambda function runtime (Python 3.7, Node 10, etc.): Node 24

[TalUsvyatsky]

Hey @holzerch thanks for raising this, we'll take a look shortly!