experimental AWS Lambda Function support

[tom-pytel]

Explicit AWS Lambda Function plugins in their own aws/ subdirectory. Manual wrapping of AWS handler functions is required (much like the Azure Functions plugin), see the README. The following have been added:

• AWSLambdaTriggerPlugin a generic wrapper which should work with all types of function triggers, but at the cost of information and linking back to calling endpoint.
• AWSLambdaGatewayAPIHTTP specific wrapper for GatewayAPI HTTP type triggers, stores HTTP info and status code and allows linking back to calling endpoint.
• AWSLambdaGatewayAPIREST same as above except for the GatewayAPI REST type trigger.
• agent.flush() mechanism for synchronizing on segment data send. This is needed for AWS Lambdas because AWS freezes processes in between invocations.
• ContextManager.removeTailFinishedContexts() to remove any finished spans from a context to break a parent-child chain which is invalid because sequential independent invocations of a handler are executed in inherited async contexts of previous runs instead of being executed hierarchically like most servers do (for AWS Lambda functions).

I will send up the component IDs to the main skywalking repo once tests are passed.

[kezhenxu94]

And please check the CI failures

[tom-pytel]

Will merge when main sw repo accepts component IDs.