AWS::ElasticBeanstalk::Environment - SolutionStackName change without replacement

## AWS::ElasticBeanstalk::Environment-SolutionStackName change without replacement

Elastic Beanstalk supports changing the solution stack name without replacement. For example, you can do so using the [CLI](https://docs.aws.amazon.com/cli/latest/reference/elasticbeanstalk/update-environment.html) with this command:

`aws elasticbeanstalk update-environment --solution-stack-name "64bit Amazon Linux 2018.03 v2.7.6 running Python 3.6" --environment-name "Environment1"`

That will update the solution stack in place.

[Managed platform updates](https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/environment-platform-update-managed.html) also perform in place updates without environment replacement.

Using the console web UI to change the solution stack also performs an in place update.

However, CloudFormation always replaces the Beanstalk Environment when the SolutionStackName changes; this is documented at https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-beanstalk-environment.html where it says "Update requires: Replacement"

This restriction is very troublesome since environments that have a "CNAMEPrefix" specified cannot be replaced.

Can you please implement updating of SolutionStackName without replacement in CloudFormation?

## 6. Category (required) - Will help with tagging and be easier to find by other users to +1

Use the categories as displayed in the AWS Management Console (simplified):

1. Compute (Elastic Beanstalk)

Start with the CloudFormation AWS::ElasticBeanstalk::Environment documentation and compare its SolutionStackName replacement behavior with the Elastic Beanstalk update-environment CLI command and managed platform updates. Done means CloudFormation changes SolutionStackName in place without replacing an environment, including one with CNAMEPrefix; the issue provides no repository files or tests to run.

Written by the indexing model from the issue text.