[BUG] AWS SIGv4 signer does not fully implement TransportRequestPromise

[u873838]

What is the bug?

The AwsSigv4SignerTransport.request method does not return a Promise that implements all of the TransportRequestPromise members.

opensearch-js/lib/Transport.d.ts

Lines 150 to 153 in 27c464f

	export interface TransportRequestPromise<T> extends Promise<T> {
	abort: () => void;
	finally(onFinally?: (() => void) | undefined | null): Promise<T>;
	}

opensearch-js/lib/aws/shared.js

Lines 80 to 81 in 27c464f

	class AwsSigv4SignerTransport extends Transport {
	request(params, options = {}, callback = undefined) {

How can one reproduce the bug?

Create a new Client that uses the AWS SIGV4 signer.
Then attempting to call .abort() on the returned Promise of any of the client API methods will result in a TypeError being thrown.

What is the expected behavior?

The method should exist on the Promise returned by the Transport; in-flight requests that are SIGV4 signed should be abortable.

Do you have any additional context?

The 3.X fix is to accept an AbortSignal parameter on API methods which will allow in-flight requests to be cancelled.

[dblock]

Does this need to wait for 3.0? Care to contribute to the current version?