Redesign AWS SDK V3 instrumentation to use middleware

[willarmiros]

Issue #, if available:
#411

Description of changes:
This change redesigns the AWS SDK V3 client instrumentation to use the AWS SDK's Pluggable interface, which makes all the instrumentation middleware-based instead of a hybrid solution of middleware and monkey-patching. There was an original plan to vend solely a plugin, which customers could use like:

s3.middlewareStack.use(AWSXRay.getXRayPlugin());

However, I decided to stick with the original user experience of:

const s3 = new S3({});
AWSXRay.captureAWSv3Client(s3);

This is for 3 reasons:

1. The former was very difficult to make work with manual mode, where a Segment must be manually passed in to the plugin by the user. I was constantly running into this issue when trying to test it with a sample app: Type 'DynamoDBClient' does not satisfy the constraint 'SmithyClient'. aws-sdk-js-v3#1803
2. The latter experience is more idiomatic for X-Ray users, compared to how instrumentation was done for AWS SDK v2 and all other AWS SDKs across languages
3. The latter is more extensible to OpenTelemetry, which requires an Otel-based API to be used for instrumentation as opposed to using a library's API (like middlewareStack)

I was still unable to get the latter API to work perfectly with TypeScript, because I would still get the error described in aws/aws-sdk-js-v3#1803. But a workaround was to just cast the client to any while instrumenting, which is not ideal, but worked once I did it.

const s3 = new S3({});
AWSXRay.captureAWSv3Client(s3 as any);

Also, tests will not pass because I've removed the transpiled JS from source control, I will add the necessary lifecycle hooks to get tests & publishing working later. Just wanted eyes on the code ASAP.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[willarmiros]

@trivikr @AllanZhengYP please review

[trivikr]

Suggested change

	const { extendedRequestId, requestId, httpStatusCode: statusCode, attempts } = res.output?.$metadata || res.$metadata;
	const { extendedRequestId, requestId, httpStatusCode: statusCode, attempts } = res.output?.$metadata;

The $metadata is always stored in output, so res.$metadata can be removed.

Example deserialize function of listTables command which populates $metadata https://github.com/aws/aws-sdk-js-v3/blob/e6080b303b0934ecec36c9284e0530d4129bb79e/clients/client-dynamodb/protocols/Aws_json1_0.ts#L3379-L3394

This parsed data from response is stored in the output in deseiralizerMiddleware https://github.com/aws/aws-sdk-js-v3/blob/e6080b303b0934ecec36c9284e0530d4129bb79e/packages/middleware-serde/src/deserializerMiddleware.ts#L20-L24

[willarmiros]

Actually that parameter can be either a response object or an error object, and the error object has $metadata populated on it directly. However, I agree that this is a bit of an anti-pattern design so I'll make separate parameters for them.

[trivikr]

Is throwing an Object instead of Error expected in Xray SDK?

[willarmiros]

What do you mean? We construct the errObj to record it in the X-Ray subsegment, so it conforms to our data model. But after recording it we just throw the original caught error.

[trivikr]

My bad, I mistakenly read as errObj being thrown. There's no issue here.

[codecov-commenter]

Codecov Report

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