AWS::EC2::VPCEndpoint - [Enhancement] - Output-PrefixId(Gateway)

AWS::EC2::VPCEndpoint Return Values supports interface type endpoints, but in order to use Gateways in SecurityGroup Egress rules it needs to return the Prefix Id, which they currently don't.

## Expected behavior

It should return the PrefixId required for the Gateway endpoint just created. Currently these have to be looked up via a AWS CLI call. For us, we had to make a hardcoded mapping table in the template.

```json
{
"ap-south-1": {"s3": "pl-78a54011", "dynamodb": "pl-66a7420f"},
"ap-northeast-1": {
"s3": "pl-61a54008",
"dynamodb": "pl-78a54011",
},
"ap-northeast-2": {
"s3": "pl-78a54011",
"dynamodb": "pl-48a54021",
},
"ap-southeast-1": {
"s3": "pl-6fa54006",
"dynamodb": "pl-67a5400e",
},
"ap-southeast-2": {
"s3": "pl-6ca54005",
"dynamodb": "pl-62a5400b",
},
"ca-central-1": {
"s3": "pl-7da54014",
"dynamodb": "pl-4ea54027",
},
"eu-central-1": {
"s3": "pl-6ea54007",
"dynamodb": "pl-66a5400f",
},
"eu-north-1": {"s3": "pl-c3aa4faa", "dynamodb": "pl-adae4bc4"},
"eu-west-1": {"s3": "pl-6da54004", "dynamodb": "pl-6fa54006"},
"eu-west-2": {"s3": "pl-7ca54015", "dynamodb": "pl-b3a742da"},
"eu-west-3": {"s3": "pl-23ad484a", "dynamodb": "pl-abb451c2"},
"sa-east-1": {"s3": "pl-6aa54003", "dynamodb": "pl-60a54009"},
"us-east-1": {"s3": "pl-63a5400a", "dynamodb": "pl-02cd2c6b"},
"us-east-2": {"s3": "pl-7ba54012", "dynamodb": "pl-4ca54025"},
"us-west-1": {"s3": "pl-6ba54002", "dynamodb": "pl-6ea54007"},
"us-west-2": {"s3": "pl-68a54001", "dynamodb": "pl-00a54069"},
}
```

## Helpful Links to speed up research and evaluation

https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-prefix-lists.html
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-vpcendpoint.html#aws-resource-ec2-vpcendpoint-return-values
https://docs.aws.amazon.com/vpc/latest/userguide/vpce-gateway.html

Start with the CloudFormation AWS::EC2::VPCEndpoint return-values documentation and compare its interface endpoint outputs with the gateway endpoint behavior. Then review the linked EC2 describe-prefix-lists and VPC gateway endpoint documentation. Done means the created gateway endpoint exposes the required PrefixId without a hardcoded regional mapping.

Written by the indexing model from the issue text.