feat(events): support customer managed key for event bus (#30493)

### Issue # (if applicable)
N/A

### Reason for this change
Amazon EventBridge supports Customer Managed Key for Event Bus since 2024/5.
But current L2 Construct does not support CMK.

For more information, see [Amazon EventBridge now supports Customer Managed Keys (CMK) for Event Buses](https://aws.amazon.com/about-aws/whats-new/2024/05/amazon-eventbridge-cmk-event-buses/?nc1=h_ls).



### Description of changes
Add `kmsKey` property to the `EventBus` class


### Description of how you validated changes
Add unit tests and integ tests.



### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

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

packages/@aws-cdk-testing/framework-integ/test/aws-events/test/integ.eventbus-customer-managed-key.js.snapshot/eventbue-customer-managed-key.template.json

@@ -0,0 +1,144 @@
+{
+ "Resources": {
+  "KmsKey46693ADD": {
+   "Type": "AWS::KMS::Key",
+   "Properties": {
+    "KeyPolicy": {
+     "Statement": [
+      {
+       "Action": "kms:*",
+       "Effect": "Allow",
+       "Principal": {
+        "AWS": {
+         "Fn::Join": [
+          "",
+          [
+           "arn:",
+           {
+            "Ref": "AWS::Partition"
+           },
+           ":iam::",
+           {
+            "Ref": "AWS::AccountId"
+           },
+           ":root"
+          ]
+         ]
+        }
+       },
+       "Resource": "*"
+      },
+      {
+       "Action": [
+        "kms:Decrypt",
+        "kms:DescribeKey",
+        "kms:GenerateDataKey"
+       ],
+       "Condition": {
+        "StringEquals": {
+         "aws:SourceAccount": {
+          "Ref": "AWS::AccountId"
+         },
+         "aws:SourceArn": {
+          "Fn::Join": [
+           "",
+           [
+            "arn:",
+            {
+             "Ref": "AWS::Partition"
+            },
+            ":events:",
+            {
+             "Ref": "AWS::Region"
+            },
+            ":",
+            {
+             "Ref": "AWS::AccountId"
+            },
+            ":event-bus/eventbuecustomermanagedkeyBus178EB991"
+           ]
+          ]
+         },
+         "kms:EncryptionContext:aws:events:event-bus:arn": {
+          "Fn::Join": [
+           "",
+           [
+            "arn:",
+            {
+             "Ref": "AWS::Partition"
+            },
+            ":events:",
+            {
+             "Ref": "AWS::Region"
+            },
+            ":",
+            {
+             "Ref": "AWS::AccountId"
+            },
+            ":event-bus/eventbuecustomermanagedkeyBus178EB991"
+           ]
+          ]
+         }
+        }
+       },
+       "Effect": "Allow",
+       "Principal": {
+        "Service": "events.amazonaws.com"
+       },
+       "Resource": "*"
+      }
+     ],
+     "Version": "2012-10-17"
+    }
+   },
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
+  },
+  "BusEA82B648": {
+   "Type": "AWS::Events::EventBus",
+   "Properties": {
+    "KmsKeyIdentifier": {
+     "Fn::GetAtt": [
+      "KmsKey46693ADD",
+      "Arn"
+     ]
+    },
+    "Name": "eventbuecustomermanagedkeyBus178EB991"
+   }
+  }
+ },
+ "Parameters": {
+  "BootstrapVersion": {
+   "Type": "AWS::SSM::Parameter::Value<String>",
+   "Default": "/cdk-bootstrap/hnb659fds/version",
+   "Description": "Version of the CDK Bootstrap resources in this environment, automatically retrieved from SSM Parameter Store. [cdk:skip]"
+  }
+ },
+ "Rules": {
+  "CheckBootstrapVersion": {
+   "Assertions": [
+    {
+     "Assert": {
+      "Fn::Not": [
+       {
+        "Fn::Contains": [
+         [
+          "1",
+          "2",
+          "3",
+          "4",
+          "5"
+         ],
+         {
+          "Ref": "BootstrapVersion"
+         }
+        ]
+       }
+      ]
+     },
+     "AssertDescription": "CDK bootstrap stack version 6 required. Please run 'cdk bootstrap' with a recent version of the CDK CLI."
+    }
+   ]
+  }
+ }
+}