Support for retrieving SSM SecureString values as Parameters

### Name of the resource

AWS::SSM::Parameter

### Resource name

AWS::SSM::Parameter::Value

### Description

I am trying to configure an ELB for auth via OIDC. To do this, I have to pass in a shared secret as a property, namely as part of `AWS::ElasticLoadBalancingV2::Listener/Properties/DefaultActions`.

My customer is currently not allowing use of Secrets Manager. They do allow SSM Parameter Store with SecureString types, but I'm unable to retrieve the _value_ of a SecureString at build-time, as I would by doing:

```
Parameters:
SomeString:
Type: AWS::SSM::Parameter::Value
```

(as per [the docs](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html#aws-ssm-parameter-types))

I'm unable to use the [dynamic approach](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/dynamic-references.html#dynamic-references-ssm-secure-strings) because that approach only supports 11 resources for SSM Secure Strings...

Why is retrieving the value of a SecureString not supported? If it's for security reasons, please allow customers to make that choice and if so use `NoEcho` to mitigate some risk.

As it stands, there is no way to pass a secret in to CF for use within the template except via Secrets Manager, which removes all choice from customers.

### Other Details

Refs:

* https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html#aws-ssm-parameter-types
* https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/dynamic-references.html#dynamic-references-ssm-secure-strings
* https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html#parameters-section-structure-properties

Review the AWS CloudFormation parameter-type and dynamic-reference documentation linked in the issue, starting with AWS::SSM::Parameter::Value. Define the supported retrieval behavior and security constraints; done when CloudFormation can expose SecureString values for uses such as ELB listener actions, or documents why this remains unsupported.

Written by the indexing model from the issue text.