fix(apigatewayv2): export newly graduated apigatewayv2 modules (#28250)

The API Gateway V2 modules which were graduated to stable with [2.112.0](https://github.com/aws/aws-cdk/releases/tag/v2.112.0) were not added to the main package exports. In particular:

- aws-apigatewayv2-authorizers
- aws-apigatewayv2-integrations

Closes #28239.

Now, I am not completely familiar with JSII and the CDK, so this may be only one part of the required solution to include these missing packages. 

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packages/aws-cdk-lib/index.ts

@@ -8,6 +8,8 @@ export * as aws_amplify from './aws-amplify';
 export * as aws_amplifyuibuilder from './aws-amplifyuibuilder';
 export * as aws_apigateway from './aws-apigateway';
 export * as aws_apigatewayv2 from './aws-apigatewayv2';
+export * as aws_apigatewayv2_authorizers from './aws-apigatewayv2-authorizers';
+export * as aws_apigatewayv2_integrations from './aws-apigatewayv2-integrations';
 export * as aws_appconfig from './aws-appconfig';
 export * as aws_appflow from './aws-appflow';
 export * as aws_appintegrations from './aws-appintegrations';