Token/password generator for ElasticCache with IAM

### Describe the feature

I would like to have an option in the AWS CLI to generate a token/password for my ElastiCache (redis-compat with IAM auth enabled) cluster based on my current credentials the same way as it works for RDS, EKS and ECR.

### Use Case

To connect to ElastiCache's Redis with IAM with a redis-cli. Currently the AWS documentation has a java snippet on how to generate token (there are more on the Internet for node/python etc), but still it requires to have an external tool/scipt to deal with it.

### Proposed Solution

Add a subcommand to elasticache like in RDS or ECR to generate token/password for a given cluster

### Other Information

_No response_

### Acknowledgements

- [X] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CLI version used

1.29.21

### Environment details (OS name and version, etc.)

Linux