Environment variable for sso target directory

### Describe the feature

The awscli offers environment variables to manage the custom config and credentials locations (AWS_CONFIG_FILE, AWS_SHARED_CREDENTIALS_FILE). Please offer an additional Environment Variable to set either a complete custom config dir (currently by default ~/.aws is chosen) or offer an additional environment variable to set a custom sso sessions dir (currently by default ~/.aws/sso/cache).

### Use Case

I'm running a complex setup, separating customer environments by vscode devcontainers.
Each of the containers gets all dependencies installed and receives its own aws config directory.
In general I bindmount a local .aws (as well as .kube) directory into the container, so that access to the configs and session files is possible from outside the container as well.

For e.g. k8slens I require the .aws/sso/ location to be configurable with environment variables to the regarding bindmount folder for EKS cluster access.

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

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

### CLI version used

2

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

*nix