feat(aws-bedrock-agentcore-alpha): add gateway

[aws-rafams]

Issue # (if applicable)

Related to aws/aws-cdk-rfcs#785

Reason for this change

Not implemented yet

Description of changes

Added AgentCore Gateway

const myGateway = new Gateway(stack, 'MyGateway', {
  name: 'my-gateway-57',
  protocol: GatewayProtocol.mcp({
    searchType: McpGatewaySearchType.SEMANTIC,
  }),
  inboundAuthorizer: GatewayAuthorizer.cognito({
    userPool: userPool,
    allowedClients: [client],
  }),
  exceptionLevel: GatewayExceptionLevel.DEBUG,
  kmsKey: encryptionKey,
});

Describe any new or updated permissions being added

None

Description of how you validated changes

Integ test for gateway creation

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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

[aws-cdk-automation]

The pull request linter fails with the following errors:

❌ Features must contain a change to an integration test file and the resulting snapshot.
❌ The title scope of the pull request should omit 'aws-' from the name of modified packages. Use 'bedrock-agentcore-alpha' instead of 'aws-bedrock-agentcore-alpha'.

If you believe this pull request should receive an exemption, please comment and provide a justification. A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed, add Clarification Request to a comment.

[aws-cdk-automation]

This PR cannot be merged because it has conflicts. Please resolve them. The PR will be considered stale and closed if it remains in an unmergeable state.

[aws-cdk-automation]

This PR cannot be merged because it has conflicts. Please resolve them. The PR will be considered stale and closed if it remains in an unmergeable state.