[AWS::CodeBuild::Fleet] - [Coverage] - add reserved capacity fleets with VPC-support

### Name of the resource

AWS::CodeBuild::Fleet

### Resource name

_No response_

### Description

Normally CodeBuild provides only on-demand fleets, which are destroyed when the build finishes. Now, **CodeBuild also offers reserved capacity fleets with VPC-support** (EC2 that are maintained by CodeBuild) - These hosts remain available to receive subsequent build requests, which reduces build start-up latencies:
* https://github.com/aws/aws-codebuild-docker-images/issues/526
* https://aws.amazon.com/de/about-aws/whats-new/2024/05/aws-codebuild-connecting-vpc-reserved-capacity/

Following the ["Working with reserved capacity"-docs](https://docs.aws.amazon.com/codebuild/latest/userguide/fleets.html), the API Reference should already Support Reserved Capacity for [CreateFleet](https://docs.aws.amazon.com/codebuild/latest/APIReference/API_CreateFleet.html), [UpdateFleet](https://docs.aws.amazon.com/codebuild/latest/APIReference/API_UpdateFleet.html) and [BatchGetFleets](https://docs.aws.amazon.com/codebuild/latest/APIReference/API_BatchGetFleets.html). In order to use this capability, please add support within CloudFormation.

### Other Details

_No response_

Start with the AWS::CodeBuild::Fleet resource and the linked reserved-capacity fleet documentation, then compare the CreateFleet, UpdateFleet, and BatchGetFleets API references. Done means CloudFormation supports reserved capacity fleets with VPC support.

Written by the indexing model from the issue text.